Regret (kinda long)

So I have my now current boyfriend we have been going on two years I love him to death and occasionally we have sex obviously but anyway I had an ex before that we dates for a very short period not even a month and we had "oral sex" but nothing more he wanted sex and I didn't because I didn't love him so anyway what I'm wanting to know is how to get over the feeling of regret I have done some bad things in my past like this and there's about 4 big things I regret and I want to stop thinking about them I want to never thing about them again how do I get this feeling to go away like I have talked to my now current boyfriend and he says he's done thing he regrets but he just doesn't ever think of them because that's in the past is what he's says so how do I get the thought to go away? Please help I hate thinking about it!