Just like the title said... I don't need much help but it would be nice!

My mum's boyfriend has come over today and is staying the night but I have only really met him 1 before this and I don't know how to act or what to do.
I want to be supportive but it doesn't help when my brother already hated his guts before he even met him.

I just want to scream into a pillow right now...

Anyways How are you whoever is reading this?