Please help? Sorry this is long... I want to keep my first love, so what should I do?

Sorry this is long, but please help. Right before 7th grade, I moved to a different state. During 7th grade, I met my first love (no not as in "sex" as in I fell in love for the first time). It was amazing, and I truly was in love. During 8th grade, he left me for another girl (September). This is how I know I loved him, because the pain was indescribable. Later on, we got back together. Then he did it again (in April), with one of my friends. Hurt like hell. Finally in the summer months we started talking and once again, got back together. Then, for the THIRD time, he left me (in September, freshman year, & yes each time he left it was for another girl). The last 2 times, there was a restraining order on us, cause of my stepdad :-/ so our relationship was a secret from the entire town. Kinda felt like Romeo & Juliet lol. I can somewhat understand how that caused him to pull away, the last 2 times. Years later (restraining order is off), hes a junior. I am now in college, I graduated early with my GED because I got pregnant from a previous relationship (don't get me started) & had a baby boy, & wanted to get my degree sooner... We just reconnected & he truly is different. Hes sweet & much more relaxed, and mature. Not "stud" like, you know? He treats my son amazing. I really want this to work. Problem is, how do I let the past go? Counselling? He was my first love, & put me through hell, but we were just children at the time. It kills me cause I remember the pain he put me through, and even though he really has changed, I get scared he'll do it again. How do I completely let the past go so we can have a happy and healthy relationship? Thank you so much.