Boyfriends ex

Hannah • 23 years old and loving life at the moment! In a relationship with the love of my life, my farmer man!
So my boyfriends last relationship ended pretty badly, they both happen to work on the same farm and she nearly killed him by nearly running him over in a tractor. She tries talking to him but he doesn't want anything to do with her. When me and my boyfriend first got together she followed me on Instagram and liked a load of my photos, then promptly unliked them and unfollowed me.
My boyfriend got a phone call from ones of his good mates last week saying that he is seeing my boyfriends ex. He knows what happened between them and that she nearly killed him, it's made things really awkward between my boyfriend  and his mate, and we can both see it ending in my boyfriend losing his mate, which is a shame as they were really good mates.
Basically I don't know what to do. I'm always there for my boyfriend and he knows it, but he said it does keep playing on his mind and I don't know how to keep his mind off of it...
Any advice would be great thanks! 😘