<human>: Summarize the given text in a few sentences.

I caught my BF talking to his ex(they have a son) a lot more.   She is asking him to do more things with her & him since she broke up with her fiancee.   At first, I was glad he was getting to spend more time with his son but she is now asking him over for dinner, going to lunches, exchanging emails on things other than their kid.  He is sending me the same items(she posts them to facebook is how I see them)  I am very good at picking up on nuisances in character & he has been a little off for the past few months-working out, eating better, change of wardrobe.   We talk about her & his son but he isn't as forthcoming & talks bad about the exes' fiancee & doesn't have a disparaging remark to say about his ex who cheated & is one of the most self absorbed people I have come across.  I know he lied to me about his whereabouts a few nights but when I confronted him, he denied & turned it on to me as not being able to handle him having an ex.   I didn't pull the out the proof & confront him & have tried to put it behind me/us & trust but he keeps doing things that make question. I feel like a fool & coward for not standing up for myself.
<bot>: I didn't confront my BF lies about his ex right away with my evidence(it could potentially involve others) & now don't know how to handle the situation.