How do i start trusting my husband again?

ok well me and my husband have been married for almost a year now. we have been together for 3 years,(we met in high school) he graduated his senior year when i was in my sophmore year.he joined the marines and was stationed in virginia while i was in pensylvania. i was living at home with my dad and stepmom. my stepmom was abusive physically and emotionally so when i was 17 in my junior year i moved to my moms house in oklahoma. me and my husband were having difficulties with staying together we were always on and of and it seemed like i was always making the mistakes with messing around with guys.. i started getting into drugs and alcohol and one time when me and my husband were split up i lost my virginia. i was extremly drunk and i dont even remember it. that really hurt my husband cause he wanted to be my first. and he started to not trust me. we have been through MANY ups and downs and breakups. he actually got a gf at one point and while he was with her i was getting ready to move back to pa because my mom wasnt mentally stable to take care of me. i was so excited to leave because my husband was in pa visiting. we ended up having sex.(i was and still am deppley in love with him.) though the next day he called me and told me he had a gf and he lost his virginity to her. i was heartbroken! i then looked at his facebook and saw that he was telling this girl he loves her! he told me he wanted to be with me and so he brokeup with her and i gave him the second chance. i was moving around living place to place cause i always had no where to go and then i moved in with my husbands mom...she was moving so i could stay for long. his mom was telling him that he should marry me and i can live with him so when i turned 18 thats what we did. i have done everything to show him he can trust me throughout this past year and now he does i take marriage very seriously i believe in the vow and commitment, though i cant trust him. during this past year he has talked to his ex 2wice and lied to me about it i had to find it out myself. and most recently he was texting this girl and was calling her cutie. im scared that he doesnt love me, and maybe he just felt bad because i would have no where else to go. but at the same time i think about how much fun we have we are both very similar and he does say he loves me. it just scares me cause how do i know that he is not gonna do it again? i dont want to keep getting hurt like this. i want him to commit to me and prove that hes not going to hurt me again. i just dk where to start with trusting him. im so scared. I NEED HELP. i dont want to end my marriage and he says he doesnt either, but how can we fix all of this?