I mean I’m mad, but should I bring it up?

My partner has been having trouble getting into his GMAIL because he forgot his password, this morning I did the recovery mode and got into it, anyway as it opened I saw he had 2 Facebook messages from a girl, that used to always try and get with him before we had gotten together (his Facebook & Gmail are connected) so that pissed me off, I went to go into his FB to see what the messages said but they were deleted. BUTTTTTT then I saw a message from one of his cousins girlfriends, who we’d only just met a few weeks ago, who I already questioned why his friends with her on FB AND inboxing her even when her BF was at our house and had no idea she was inboxing him, and cos if I added one of my cousins fck buddy’s he’d get mad and about a week ago he deleted her, but the message I read was only his reply and by the time I took a screenshot he had deleted that as well and it had said “my Misses going through my msg you later if *your boyfriends name* msg me sweet” i mean that msg alone pisses me off, it could be innocent but why would he delete it and tell her he will msg later cos I’m going through his msgs and omg I’m just mad idek. What do ya’ll think? His track record with this BS isn’t clean either