Help. Husband and my father.

I've been with my husband for 5 years, been married for two. We have a three year old son and I just found out that I am three weeks pregnant. My father recently lost his job and needed to stay with us for a couple of days until he could get his own place. I talked to my husband and he agreed. As soon as my father got here my husband has been pressuring me constantly to find a place for my dad. I have been looking non stop and so has my dad. My husband finally blew up and made many horrible comments about my father to me or to my father himself. He even said to him 'just go find a place and die'. It even got to the point where my husband is threatening to leave me because of this. Thankfully my in laws are great people and are letting my father stay with him til he finds something. My husband and father have always gotten along before this. My husband takes a lot of pain medication for a broken back and torn elbow tendon. I want to believe that this isn't who my husband really is and it's the pain meds making him act this way. I feel so nervous, stressed and upset. I don't want to lose my unborn child because of it. I only work part time and don't have anywhere I can go. Any kind words of encouragement or advice would be greatly appreciated.