Am i being unreasonable? TMI

My boyfriend and I live together and are expecting a baby. Things are bumpy and we get into arguments often. One thing we get into arguments about is him watching porn. It bothers me point blank period. I’ve discussed this with him and I told him I don’t care if you watch it, it bothers me but I’m not going to tell you what to do. The porn itself bothers me but not as much as him lying and hiding it. This post isn’t about that though it’s about something a bit worse. Let me start off by saying we have a pretty healthy sex life this morning I wasn’t really in the mood and he got a little upset with me. Flash forward to about an hour ago, we get home from him picking me up from school and as I lay down I notice one of the blankets was wet. I had pulled it up over me and that’s when I smelled cum. I giggled and said damn babe couldn’t wait for me to get home. He goes that’s not cum that’s water. Cue about 5 mins ago we were cuddling and I go dang still in the mood and he’s like so what I jerked off. When I ask him why lie about it that it’s not that big of a deal he tells me that him lying about it isn’t that big of a deal and I’ll get over it. If you’re going to lie about something that small and irrelevant what else would you lie about? Am I unreasonable for eating upset with him lying? This isn’t the first time I’ve caught him in a lie either.