A.F.
I have had these same problems before. I know how it is. It is going to be tough for a while. What you guys really need to do is sit down and talk with each other. Not yelling and screaming. No fighting. Just talking. If need be, get someone to mediate. (preferably someone who won't talk sides) You need to tell him how you feel and he needs to tell you how he feels. A baby is a big change and it's tough on everyone. Just remember, it's not just about you or just about Kenny anymore, but it's not just about the baby either. (I know with my first that all I did was think about the baby and not my boyfriend. You have to set some time for Kenny too.) It's about all of you. You guys have a baby to worry about and he depends on both of you and you guys depend on each other. Yes you guys are going to be tired and cranky alot, but you just have to get through it. When his snaps at you, or you at him, you guys just have to remember "maybe he/she is stressed out today and doesn't know how to deal with it." Try doing that and then later, after you guys cool down, try sitting down and talking about it. For example, you could say something like "[insert name or pet name here], I don't know if you realize it, but you snapped at me today and it kind of hurt my feelings. Is there something wrong that you want to talk about? Did the baby stress you out today?" or something like that.
Like I've said before, just remember that things are going to be hard and stressful for a while. You guys just have to help each other through it. I know you're having a hard time with having to adjusting to college, new baby, and just going back to work all while trying to keep your relationship from falling apart...but maybe he's having a hard time too. Maybe he just really misses you and misses the way things use to be. All new parents go through this at some point or another.
Well, this is getting kind of long. I hope this helps! Congrats to both of you on your baby boy! Good luck! :D