Gerda - So very sorry your MIL added to your burdens. Some people are incapable of offfering empathy. And she seems to think that blood over-rides even the worst behaviors. I do not agree with this. But, there it is.
I originally had so many words written out here for you to read, but nothing sounded quite right.
I continue to pray for you. Let the feelings of grief, sadness, rage, and loneliness wash over you and drain away. Take one moment, one hour, one day at a time. Take a few moments throughout the day just for yourself. And ask for help if you need it. For the work on the apartment, perhaps members of your church can step in for a work day and help out?