I've been seeing someone for a year. Lovely guy, very supportive, kind, generous etc and I love him very much. I had a very abusive relationship previously so I don't know whether that's clouding my thought processes (sort of fight or flight response type thing) but a couple of days ago he revealed he'd had a fling with a close female friend of his (who I've met and is nice). I'm just a bit taken aback that he didn't mention it before now (there have been a couple of times where conversation could've easily led to his mentioning it) and I just feel a bit weird about it.
I know I need to give my head a bit of a wobble but I can't work out why I feel a bit odd and how to get myself out of this negative headspace. He assured me there is nothing more to it and he doesn't think of her romantically which I believe, so why can't I shake off this horrible feeling and just get over it. It shouldn't be a problem I know, but it is. Any wise words to help me tackle these negative feelings and get over myself?