Am I over reacting?

I have a 16 month old and a 3 week old. Since I was about 35 weeks pregnant my husband has gotten into the habit of coming home from work (an office job) at 530pm and going straight to bed and sleeping through the night until he has to get up for work at 630am the next morning. This leaves me to take care of both kids all day and all night completely alone and really having no adult companionship what so ever the majority of the time. We have a very happy marriage and are each other's best friend but it's very frustrating to deal with this because I can NEVER sleep in. I'm beyond exhausted taking care of two kids under 2 and he doesn't seem to get it. We've talked about it before and he's told me he'll stop but he hasn't. He goes to bed at 530 at least 3 times a week and I'm completely at a loss at what to do. He came home today and literally went straight to bed and I just feel like crying. Do I have a legitimate reason to be annoyed or am I being hormonal and ridiculous because of baby hormones?