Bio Dad Suddenly Back in Picture

This is way beyond the paygrade of reddit, but I'm really just going to vent, and if anyone has any advice they want to share because they are familiar with the situation, I'm all ears.

TL/DR: Bio dad to my 10 year old is suddenly back in the picture and wants to be involved after 10 years of absence, and never once acknowledging her existence. He also plays the victim.

Background:

My wife, and my two daughters. My oldest is technically my adopted daughter - I'm on the birth certificate, been involved in her life as her father since she was two, legally adopted when she was 5. Absolutely adore her, and she is my oldest daughter. I am her father - period. Both as per the courts and my actions/role as her father. If I'm being super open I have a special bond with her because I chose her forever. I put my name down, and said I want to be responsible for her forever. She's my daughter. I'm real dad.

Complications:

After my wife got pregnant with the oldest the father refused to believe she was pregnant, and further refused to believe it could be his. My wife decided not to push this because (in her own words) "if he's not going to be responsible, it's not my job to make him take responsibility, and I don't want him being the father in that case anyway." She ended up being briefly married to another guy who allowed her to put his name on the birth certificate, but allowed me to take his parental rights during the adoption process. He's still moderately involved with her life, and is a valuable relationship for her mental health. I have a good relationship with him, and while I miss her during the weekends she spends away with him and his family, I know it's great for her. She's grown up with the belief that he as her bio dad - not a great decision, but I guess the alternative they saw at the time was to tell her that her bio dad didn't want to believe she existed, so this was their best alternative they saw. Anyway, I met and got involved with both of them (wife + daughter) 2 years after this.

Yeah, this whole thing is weird. I get it. Could have been handled better from the beginning, but I don't know how I would have done any different and been successful. Anyway, I saw the Facebook messages from 2012 with this real bio dad; they are a TRIP from that guy's weird brand of copium. She blocked him shortly thereafter on facebook, and moved on.

Present Day:

My oldest is 10, and her bio dad shows up by calling my wife accusing her of stealing 10 years of his fatherhood. I think this is a complete joke; he decided to leave, and in ten years while I was the guy scooping my oldest daughter up when she skinned her knee, teaching her how to ride a bike, taking her to and picking her up from school, and pediatrician appointments, the zoo, the aquarium, helping her learn her numbers and the alphabet, working countless mornings and evenings on her arithmetic, Fry's sight words, reading/writing, dealing with bullies at school, all the things. While I was doing all this, THIS guy was off fucking around somewhere convincing himself for the last 10 years that he didn't have a daughter. Until last weekend when I guess he decided "ah shit, I feel too guilty, better try to do something so I don't feel this way." No clue what his reasonings really are.

So now he calls, and wants to be a part of her life. He has since moved to and lives in Texas, we are in Colorado. I've never been super comfortable with the lie of her bio dad being this other guy I have a great relationship with, but at the same time had no idea how to break that news to her. She's fucking TEN years old - she's suppose to be playing with her friends, not dealing with this stupid adult drama. But here we are.

Already consulted my attorney, and even if he wanted to pursue legal action he has no case. It's clear he was informed about the pregnancy and child, but chose not to pursue fatherhood. He also tried to blame my wife and facebook for blocking him, but that's equally absurd to me. People have been communicating just fine without facebook; and you don't get served a summons as far as I know on Facebook, so shutup jackass. OH! And this guys social media is an unhinged NIGHTMARE of conspiracy theories! I've never known a REAL flat earther, but apparently there is one right here.

Can't imagine anyone is in or has been in a similarly messed up situation all things considered, but there's probably some adjacency out there. Called my oldest's therapist up (just trying to normalize therapy for the kids so they know it's an option without stigma as they get older) and she's helping put together a plan for this. I just wish the plan was "tell the bio dad to go away forever" but that's me being selfish.

No contact yet. Just getting started on messaging.

Anyway, rant over!