If you're still not speaking to DF then write him a letter explaining how much all this is upsetting you.

If he doesn't do anything, then tell him that he needs to chuck out his friend and tell his mum not to come and if he won't do it that you will do it as your ob has insisted that you not be put under any extra stress.

It's really not on. You need some time to chillax and you can't do that with other people in the house. I'm exactly the same.