So after a LTR ended not too long ago, my first love/ex comes back into my life. She left me twice in the past. When I was like 19 and then again when I was 21. Now we are both almost 30. She did ride the CC real good after me but career wise accomlished nothing (working in bars mostly). I meanwhile finished a competitive degree and started my career. One of the reasons she left me was that I wasnt social enough and too focused on my studies (in my field you dont have a choice but to study day and night for years). Now we started having sex again and I cant say i dont enjoy it. She is hot. Each time after sex I am so sure that i wil end this..but 3 hours later with her butt pressed against my crotch Im already not so sure anymore. its a nightmare. she is psychologically NOT stable and looks to me like the damsel(amsel?) in distress. this plus her being hot makes it so hard to resist.
Help me out brothers.

Edit/Uptdate: Thanks for the tough love. For everyone being concerned about pregnancy and STDs. Of course I always wore a sock (you really cant trust on the other one taking the pill). We had some good f****** in the last weeks. Did everything I wanted to when we were younger. But looking at her sleeping next to me ut just reminded me that I can´t stand her. So I ended it. Told her that I wont have a relationship with her again because I just can´t trust her. She told me I was the only guy she ever really loved. She asked what our friendship would entail. I told her she can write some time. So why did I end it now already? Because I dont believe most woman, including this one, are evil. They just follow their instincts. There is no need to inflict unnecessary pain by fooling her for months.