Should I be mad about my boyfriend playing strip pool?

Earlier that day my mom’s car broke down at the movies. I called my b/f as last resort anyway to ask if we would come give us a jump. He told me he was in the middle of a poker game w/ his family and the Buckeyes were on so I could tell he really didn’t want to come help. Once I heard his lame ass excuse I got a little angry and told him to forget about I don’t want his help. Later that night, I went over a friends house and hung out. I decided to go see my b/f since I hadn’t seen him all day. I got to his house and walked in, not even having taken my shoes off yet I heard my b/f and some other people talking about me.. I heard “yeah she would be mad if she came down and she was naked or Willie (my b/f) naked” Yeah there right I would have been mad and I already was from the shit earlier. I ended up finding out my b/f was playing strip pool with 2 other dudes and a girl who was engaged to one of the boys. Also I found out that she and her finance were down to their underwear (which I found out by a friend). When talking to my b/f about this he said it never got that far where someone got naked and they were playing for socks. I asked why would he play knowing it would piss me off his response was he had confidence in his game. my question is why would he do that knowing it would piss me off?, Why would he play with another girl whom he knows I have problems with?. I just don’t understand.