This is always an issue with males! Whatever they do with other girls is their right (!!) and they can never tolerate any such fling of their partner.Morally, you do not have right to hurt her by repeatedly raising her past. Accept her past and forgive her for the same. Even thoughts may come but you need not to always clarify with her or torture her. Exercise self control over thoughts and it’s discussion with her. If you really think that she is a nice woman then does not she deserve forgiveness on this issue?! Just think about it.