Is it over for us?

Me and my boyfriend had a conversation yesterday about how I was uncomfortable with how young his ex girlfriend was, and that it has been bugging me for a while now. She was a minor when they started dating, and it doesn’t sit right with me. He told me that he thought that she was a bit older than she actually was. He thought she was 17, when she was actually 16. My boyfriend was 21. He told me that he never asked for her age when they started dating and that he just assumed that she was 17 because most of her friends were that age. But she was still a minor. When he later in the relationship found out her actual age he said that he thought it was a bit weird but he didn’t mind because he “was in love”. None of their family said anything about the age gap. Lately I have gotten intrusive thoughts about their relationship where I find myself thinking about his relationship with a child, and they occur when we sometimes cuddle or have sex. There is nothing he can do or say that will make it disappear off my mind, and I will probably always find it disturbing that my boyfriend has been with a minor. I don’t understand how he could possibly want a romantic and sexual relationship with a high school girl when he was an adult. I love him very much and I wish that this never happened and that he never told me about his past because now I feel lost about what to do. I think his previous relationship was wrong in every way and I want to stop thinking about it. I don’t want the past to affect our relationship because it is the best thing that has ever happened to me and he is the one I want to be with forever. I don’t want this to be the end for us but I have no idea what to do or say anymore.