my past gets in the way

Tell him this...

"i did what I knew then, and now I know better..."
"i have asked forgiveness from god and he forgives me as long as I acknowledge my wrongdoings, apologize to those whom I have hurt, and promise to implement change"
if he hasn't the capacity to forgive that foregoing, which is all a human being can possibly offer, he should be ashamed of himself. Do not tie yourself to a flogging pole to be forever punished for the past. He who is without sins can cast the first stone, and it is not going to be him! You're establishing a dynamic here which will forever be in play if you do not draw a firm line about it and change it now...He will always have this shame and blame aspect with which to manipulate you. He will never respect you until you stand up for yourself. One day he will be calling you names which you will feel you deserve, until you can forgive yourself, ask for god's forgiveness and then your boyfriends...His ability or lack thereof is telling as to his character. If he can't show some depth, then dump him now, as he will only make your life miserable over time.