I have a question and need an urgent answer to it. Hope you guys help

I am in a relationship for the past 8 months and have been really happy in it(although I don't know what happiness is because I don't remember the last time I was happy). My boyfriend is a year and a half younger to me yet is my senior in college(because I dropped two years between school and college). He is a very nice guy and absolutely lovable, and am his first girlfriend. In the initial days I told him briefly about my past 3 relationships and thought he'd be fine with it, but it turned out after a few days that he wasn't able to take in the fact that I have been with others before him and started having a million questions. I answered patiently and eventually one day lost my cool as the series of questions wasn't ending. He said he realized he's having a severe retroactive jealousy and he can't help it that he's haunted by my past. He finds it too difficult to accept me as I am. Although I lost my virginity with him and never as much as even kissed any of my exes properly(only had pecks), he finds it difficult to erase such images of me with someone else from his mind. He says he'll get mad one day because it's getting out of control. We both love eachother a lot and can't even breakup(although we've tried) and it's impossible to give up. But how long will it go on? Need suggestions and help to help him recover from it.