Help!!!

Ok so my bf gets pissed when My kids father parents message me. I feel like he is just being jealous or possessive. I don't know. But he says I'm fighting to keep them close to me rather then keeping him close. Me n my ex were together for ten years and his parents play a big role in my life. Don't know what to think about this. Don't understand why it is such a big deal.  My bf says I should ignore them and never talk to them again.