It sounds like a good plan. Honestly to be comfortable you don’t even need a large place. It will be a safe and peaceful place. Grieving is very normal.

Will you be selling your house? Surely your wife is not in need of a large house if kids will live mostly with you. She could have two bedroom apartment and kids will stay in the other bedroom when visit her. Also I urge you to not buy property while not divorced yet. I think you should talk to a lawyer ASAP about best options