Constantly arguing with my boyfriend now...

Hi. I'm 8 months pregnant. My bf lost his job and things have really changed between us. He took some money from me that I had stashed without asking me and It really hurt me that he did that. Ever since he lost his job and took the money from me I've lost trust in him. He told me he was too embarrassed to ask me for money bc he sees me spending so much and he was going to return it before I knew it. But as the days went on i just look at him differently.  He's been snappy and I see his selfish immature side. I'm easily annoyed by him and I've been snapping. We've been arguing and I Am Really nervous about our baby and whether or not this is arguing and turmoil is affecting her. I want to have a healthy baby. I'm so worried . My friend says women feel like this annoyed around this time on pregnancy. My brother has been helpful around the house. Finally got a new job lined up starting Monday. But ...I'm angry with him. I'm worried and although I would really love the round the clock help with the baby I think he's too immature to live with not to mention his financial situation is crappy, horrible credit this guy. I feel stupid like I fell for a looser or something. I want to have faith that things will get better. Any words of encouragement in either direction are welcome. I'm concerned about my baby and the arguing .