You are definitely not the only one. I slept with some one nearly double my age while hypomanic (I was 21 and he was 40) I really regret it and for a long time thinking about it made me upset or feel sick.
Part of what has decreased that feeling is accepting that I'm not perfect, I'm human and allowed to make mistakes which I think is something our society doesn't recognise anymore. Yes there are consequences for some mistakes that we have to face but humans are not perfect. Our illness is just one example of that - I think our illness would be easier to live with if we didn't have the pressure of trying to live up to societies expectations of what we should be like.
Another part of what has improved things for me is time and being stable for a while. It's amazing what a good med combo can do.
Writing in a journal can help as can talking through things with a T. Good luck and you are definitely not alone.