Husband seems unhappy

So my husband and I have a 3 month old baby boy. He is amazing and we are both besotted by him. However my husband just seems very unhappy and grumpy lately. We have been butting heads big time since I have been on maternity leave and having a go at each other all the time. He is not a nasty person but the other day he snapped at me and told me to shut up, which is absolutely not on. I would never stand for that and let someone talk to me that way especially not my husband. Problem is he gets defensive if I suggest he has done something wrong. I just don't know how to brotch the subject and explain how he hurt my feelings. Having a baby has definitely put a bit of a strain on our relationship which i know is very normal. Has anyone else faced any issues like this with their partner? Any advice?