a Major Life Decision(NEED A LOT OF ADVICE!!!

Natalie
So, my bf of 3 years is planning on moving to Texas at the end of the year to be with his kids again. I completely understand that. I would never ask him to choose between me and them. 
However,
I don't want to leave my hometown in Cali, as my friends, family, job, etc is here, and I've been moving around since I was sixteen. I don't want to move. Period.
I've asked him to compromise, but he says the kids grandma, who has been raising the kids since birth( mothers not in the pic,) will not move. I feel like she controls him through the kids, and they're HIS kids. 
I don't know what to do. I have to choose to let go of him or Cali, and either decision will break my heart. I just need some advice, as this is a major life decision. Help??