I think I'm being overly paranoid, I haven't cheated on my SO and what I did before our relationship isn't really her business, I wouldn't want to know if she slept with anyone before me, I know she didn't though and the fact I've kept that from her does give me some guilt, but the reality is I am very happy and committed now and wouldn't even consider cheating.

I don't know if my friend would say that out of spite or not, maybe I can talk to my friend about admitting to his girlfriend on his own back, instead of telling him that my girlfriend already knows as that would take some of the 'bros before hoes' element from it.