how am i supposed to move on ?

long story short i was dating this girl for about 3 years on and off and we'd always find our way back to each other despite being in different relationships over the years. i have undiagnosed bipolar depression so it made it harder for me to communicate with her and vice versa. id always find myself trying to get over her somehow or when i dont think about her i turn around and shes texting me again despite getting out of a relationship with someone she left me for. shes cheated on me multiple times for three years while we were on and off and i still loved her and forgave her because i didnt want to move on and i kept being her rebound and when she would come back id welcome her with open arms. basically being sorry that she hurt me. its been a couple months since weve been in contact and i still have yet to even get closure from her. i feel like it would give me some insight on why she treated me like that however i just want to get over her. 

note: we were also long distance for all three years but came close to meeting each other throughout the course of our relationships but strict parents yk ? in in a happy relationship now but i feel as though i cant love my partner the correct way because of my ex but i love this girl to death and i dont wanna lose her. ive been in alot of toxic relationships but finally being in a happy one is a weird adjustment lol XD.

sorry for venting on here but i literally have no friends :(