12 weeks on Medimeal (Optifast)

I met with my surgeon on Friday and he wants me on Medimeal for 12 weeks prior to surgery. My BMI is over 60 and he needs my sternum to be 14" or less from the table. Currently it is 16". Looking at roughly 50lbs for this.

My diet will consist of 3 shakes a day, 1 cup of broth, some sugar free jello and water for 12 weeks. Has anyone else done this preop diet before?

I will admit I am extremely overwhelmed at this timeline and hoping other people have been through and have some sage advice from the other side of it.

I haven't tried the medimeal shakes yet, I am really hoping they aren't vile tasting. I was provided some ideas for making them more palatable (extracts, decaf coffee, mio, etc)