Hey Lost Hope, First, I'm sorry you find yourself here and find yourself in a situation quite similar to my own (7 mo pregnant and separated).
I'm no vet but I will say that the more major life decisions you can avoid right now the better. Buying a house sounds like a huge amount of pressure at a time when things are very fragile. Once again, I'm no expert but if you can find a place to rent even for 6 mo to a year you will be in a much better place to figure out where you'll live long term without scaring him away right now.
Also, I find myself counting down the weeks to having this baby and feeling like I just have to have everything figured out before my due date. The truth is this baby won't remember anything about his life until he's 2.5 to 3 years old. That gives you (and me) a solid 3 years to work through our marriage crisis before it will really impact how our kids remember their lives. It takes a lot of pressure off my back knowing that whether H and I work this out or not I can certainly see us being on much better ground in 2 years, either as co parents or husband and wife.
If you can, try to focus on not letting him get you worked up, staying healthy and active and just letting him have time to work through what he's feeling. You don't need to decide today whether things will work out or not. Save that for next week, next month or next year.
Hang in there. Sending you prayers!
BD: Aug 2012 Separated since May 2013 S born Aug 2013 Aug 2013 H agrees to consider 'baby steps toward working things out' H is/was actively seeing someone?