my boyfriend of 2 1/2 years "almost"? cheated on me, where should i go from here?

hey everyone. i just need advice. i'll try to give as much detail as possible but feel free to ask questions. i (22f) and my now ex bf (22m) broke up 3 days ago but we've been dating for 2 1/2 years up until this past monday night. a girl from his high school randomly reached out to me via instagram dms monday afternoon asking if my now ex and i were still dating because she was suspecting that he was being dishonest about his relationship status. he logged into his old snapchat account, swiped up on her story about something totally random (a kitchen remodel) and then ended up asking her if she was single, telling her that he had recently gotten out of a relationship (untrue), and asking her to plan to hang out and what she was up to later several times throughout the span of two weeks. this happened ~ 2 weeks ago on February 16th up until this past monday morning (he asked what she was up to that night along w other times). she told me she was intentionally vague about plans because he was acting suspicious and only reached out once she stalked his instagram and saw all of our photos still up (i was in his pfp and literally almost all of his posts). i couldn't help myself but to confront him right away. i asked what he did and he didn't fess up. i actually assumed that this happened about a week ago as we did actually break up about a week prior for literally a couple of hours because i found out that he was being dishonest about something else. during those couple of hours he literally was telling me that he wanted to be with me the entire time. when i assumed it was then, he did not correct me until i had more conversation with the girl and realized that this started even further back when we were 10000000% still together. so he lied even when caught. in the immediate aftermath he was awful. he basically shut down, would not let me say much to him past the immediate phone call where i first called him out on everything. he blocked me on most things but then would unblock me because (i know from experience) he was just doing it as a cry for attention since i broke up with him. i worked up the courage to send him one last paragraph over text about how he's made me feel on wednesday morning and i blocked him. when i did that, he finally felt how he made me feel with the blocking. he freaked out, tried to contact me on anything i forgot to block him on, and even asked him mom to reach out to me. i caved and unblocked him, and since then he has been legitimelty taking accountability rather than hollow "im sorrys", has been allowing me to vent as much as i want, and has been promising to change and go to in person therapy even though i keep telling him there is no way possible we can be together.

we have had other problems in our relationship. when we broke up about a week prior to this, i did it because i had found out that he had been lying to me for MONTHS about being in therapy. he would literally tell me on at least 3 separate occasions that he was "about to login to therapy" or that he "just got done with therapy" as it was supposed to be virtual. therapy was an ultimatum for him disrespecting my boundaries on porn. i told him, and genuinely mean it, that i don't care if he watches it sometimes just as long as it's not constant and that he doesn't pay for it. i issued the therapy ultimatum (therapy or we breakup) when i found out that it was still almost every day without change and he did end up paying for OF. when i found out about him lying about being in therapy, i tried to end things but couldn't stick with it. i want to be clear that his porn use IS an actual addiction. i have talked to my own therapist about it in length and she has identified it (to the best of her ability) as an addiction. which i told him about and also told him that seeking outside help is the literal only way to get help for an addiction. there had been multiple times through the "months of therapy" where i intuitively suspected him lying about doing it and i asked him to his face if he actually was and that i had suspicions. he told me to my face he was. finally, when i broke up with him for it (for those few hours) he finally came clean after i asked again. he told me that he knew it was an ultimatum for me but that he was geniunely scared to tell me that he didnt want to do it because he genuinely doesnt feel like therapy works for him (he has gone in the past but not tried very hard) and that it doesnt work for anyone. he promised to continue working on things in his own way (by tracking through an addiction app in his phone). anyways, i stayed. i wanted to work through it and i know the lying is inexcusable but i am trying to keep in mind that this is a genuine addiction.

i want to be clear that he never did hang out with that girl. he never actually knew her in high school, they never talked until this exchange. he has reached out to other random girls from high school, some he used to be friends with and some not. but to my knowledge from extensive snooping and having his location i do not think it has ever gone to this point of being unfaithful. in my mind, this has been almost cheating??? i dont know. i have been struggling with family and friends comments on respecting myself. i do respect myself. i do a lot of work in therapy (i have been going almost my whole life) and i tried to set very firm boundaries with my ex when i needed to.

where i need help - i am really truly struggling to let go of him. we lived together for 2 years. i consider his family my own, i have very meaningful relationships with almost everyone and have been to almost every family event for the past 2 1/2 years. we were going to travel together soon, had set plans to move in together, get a cat, and despite all of his lying and what you may think i do TRULY think he loves me. please dont think im delusional about that part, it's impossible to share the innerworkings and complexities of our entire relationship in one reddit post. i love him still. i understand that we can NOT be together. the ONLY inkling of hope i have is that he does genuinely go to therapy like he said he finally will and years and years down the line we could work. but my family and friends are incredibly close to me and all know what he did, i needed support. right NOW i cant get myself to stop communicating with him. i am NOT giving him passes, i am hammering it home how much he hurt me and how we can NOT be together but i dont want to lose him completely. he became my best friend too. i cant process the idea of him being completely out of my life. basically, although i KNOW he disrespcted me multiple times i don't want to completely cut contact, i don't feel like i can. what should i do?

edit - i feel like all of my dreams and plans for my future with him have just been absolutely crushed. i know that's entirely his fault and im trying to get more mad but im not to that stage yet. i feel like the cheating is hard enough to deal with, i don't feel like its fair that he gets to literally rip away so many other things from me along with the betrayal, mainly being him honestly. i loved him so deeply and passionately, and his family. if it makes any sense at all, i just want to have some contact with him so i dont lose EVERYTHING right away. i know it cant be forever.