The past is the past. If she want to be with you then she should accepted your past. As long as you don’t have feeling for your ex anymore, there shouldn’t be any problems. If make she make it as a big problem then herself has issue and you shouldn’t mention about your past or ex to her anymore. My boyfriend is way older than me and he told me everything about his life and his past. How many ex he had and how many girls he slept with, I don’t take it as a big deal. Instead I’m glad that he has had all those experiences and knows who he really loves and who he wants to share his life with. He has a good friendship with his ex brothers and still hang out with them, I don’t even mind. I told him we are not married and you have the right to see anyone you want to and you should keep his option open. But he refused to and say I’m the best for him, cuz i’m not controlling, not crazy jealousy, understanding and a reasonable person. If you know yourself that you’re a good boyfriend to her, she will never leave you but if she does then it’s her lost not yours. Plenty of fishes in the sea.