Mother in Law Problems please advise

So my mil and fil are getting divorced its a very nasty divorce she shows up at our hoise crying all the time. Anyways yesterday going thru the hubbys phone i found out that he is buying us a home well first i thought it was for my mil and i got ver upset and confronted him him about it. Turns out it was suppose to be a suprise but heres the catch... my mil is moving in with us. I just dont know how to feel or react right now. Im happy wd are finally buying our first home but im upset that he did it behind my back and that now his mom ia moving in too now until she gets back up on her feet. What the hell should i do?