I'm glad you've found such a great guy! I don't know how much my advice will help since I have the same problem, but instead of telling yourself he's gonna run or leave you or whatever start telling yourself that he's gonna stay, that he's gonna be there for you.

I've been with my bf for over a year, and like you, I'm used to being left, being used, and being cheated on all the time. I'm just now beginning to think this guy isn't gonna do that. It takes time to heal and to trust. Just give it time as it will not happen overnight.

Have you told your new bf about what you're thinking? Let him reassure you that he won't do what you fear and let him be there for you. Just let him know that you need time to trust him.