I (31m) am looking for homes with my 6 month pregnant wife (29f). She is being very erratic and I'm worried

Me and my wife got married just under two years ago and we got pregnant about 6 months ago. This will be our first child.

We've been renting our current place since Mid 2014 and we've been house hunting for about 2 and a half months now at her insistence as she always saw herself in home if we were a family. That's fine with me, I was fine with renting too but it's about time to lay down some roots.

Anyway, the whole experience has been very difficult. She'll ask me for my option and then completely disregard it. She'll say she loves a house then says she hates it a half hour later and yells at me for wasting her time or picking such a crap house to visit (even though she chose it..), demeans me in front of realtor, and so on. She's slapped me and thrown things a handful of times at home, but I can deal with that. I recognize that house seeking is stressful and I'm sure the pregnancy compounds that. She insists that we find must something before the baby arrives. It's become like an obsession.

What made me make this post is that this past week she thought she found the perfect house and I thought it was okay but if she was happy I was happy. We negotiated, and signed the papers. Maybe 15mins after we left she turns around and starts screaming how stupid I am for signing that and we've made a huge mistake. So I told my realtor who called the home's realtor and basically said/begged that we made a mistake and could he trash that agreement. Fortunately the other realtor agreed without issue though we had agreed to a nearly $20,000 deposit on paper which he could have taken if he or his clients really wanted to push the matter.

I've spoken to a few women in my life who have been pregnant namely some work colleagues and my sister and they say that these are are pregnancy hormones and it's tough but I have to deal with it just like other husbands have been doing for millennia. That's fine but I'm scared that we're going to jump into a home that we won't like and then, after the pregnancy my wife will hate it and we'll be stuck. Or we'll lose a deposit or something. I support both of us on my salary (she stopped working after we got married and is pursing a writing career) but we can't afford to take these kind of unnecessary financial hits. If we had lost that 20k..

I've tried speaking to her about this stuff (let's maybe hold off for a bit/can we get it after the pregnancy/emotion and house buying don't mix maybe/what do you think about both of is talking to someone else about this?/etc) but every time it results in her bawling, accusing me of hating her or her getting a little physical. Eggshells. I don't know what to do.

tl:dr pregnant wife is very focused on finding a house before giving birth and is making house hunting very difficult. I'm worried that we're going to make a big mistake with a house we don't like or lose money on reneging on deals.