10 weeks postpartum, resentment towards my husband

Basically, my husband will bend over backwards if I ask him to, he is great. For some reason since I had the baby nothing he does is ever good enough or right for me. This has put serious strain on our relationship. I do all the feedings bc in breast feeding (which has been such a struggle) so I am exhausted 24/7. My baby still eats every 2-3 hours at night. 
Now my husband told me that he has a work trip coming up in June to Vegas. He told me over text after he had known about it for a week. He told me bc I w mad bringing the baby to his work and he didn't want me to find out that way. This makes me sooooo furious. We have a history... He only tracked most once a year but the trips in my mind are useless, just an excuse to party with co workers. All his co workers cheat on their spouses and the girls are just awful. My husband says I don't trust him. I do trust him but I'm bulshit of the way I have to find out about this. Plus I don't want to be left alone for 4 days alone with the baby I work hard enough ... Any input would be greatly appreciated! 
Also, could this be postpartum depression? I assumed it would be being sad not mad... And I thought I was too far out..