intimacy with an ex? cheating or not?

ok so this has been bothering me for sometime now and i want to get a general opinion from you guys what would your position be if you were in my place...
both me and my girlfriend are still in touch with some of our ex's I would even say close friends with a few of them.
we have both always been open to each other that we are in touch with our ex's and ive always been fine with her remaining friends with them as a matter of fact she visited one of them recently without me "he lives in another state now" and after she visited him he visited us and i met the guy seemed like a nice guy he even stayed in my house for a few nights since she lives with her family. so I dont have any jealousy issues "at least i don't think i do"
anyway a couple of weeks ago me and her were talking, nothing specific just chatting, and the topic somehow got to her visit and i kind of sensed from her tone that she is hiding something so i asked her whats going on and she asked me not to be mad etc. at which point she confessed that one night during her visit they shared a bed and from what she was telling me that it was just cuddling but not regular cuddling like her putting her head on his shoulder but intimate cuddling "spooning etc."
now obviously Im not happy about that but I'm kind of conflicted whether that is considered a form of cheating or not???
im also very conflicted whether or not to take her word for it that it was just cuddling and nothing more... usually i trust her and believe her no problem but the fact they used to be together and then they are in a house alone sharing a bed and cuddling but nothing more kind of seems unlikely it wouldn't go further than that.
worst thing about it she knows that I would almost certainly forgive her that one time if she's honest with me and tells me "obviously she would have to cut off all communications with him"
but still logically something almost definitely happened and i just couldn't shake the feeling she's hiding something even after she told me they cuddled!!
what do you guys think? what would you do in my situation?

please give your honest opinion, don't worry I'm not going to base my decision on your answers nor would i be offended by them everyone is different and everyone has their own opinion.
im just looking for some perspective or advice or if someone had a similar situation how that turned out