boyfriend fighting over the past

so my boyfriend and I have been together for almost 2 years now. But two months ago we decided to make it official. ever since we have been together we have fought about my past. before we were together I didn’t have much respect for myself, I would do things with other boys and I was a very flirtatious person and I wouldn’t dress very appropriately. I have so many feelings for my boyfriend I love him so much but out of nowhere on occasion he will bring up things that make him jealous and he will take his anger out on me about my past he will get very aggressive with me and constantly tell me I’m lying. He always gets in his head and makes scenarios up and believes them. I don’t know what to do I love him so much and he loves me and I understand he gets jealous but I don’t know how I can help him, any tips?