Monster mil

My husband and I are expecting our second child this fall, and we have yet to tell his parents. My wishes are not to say to them. They were barely involved with our oldest son and their first grandchild. They are indifferent towards him in comparison to their granddaughter from their oldest son. I think it is best to stay away from his parents because my mil is selfish and always looking for a pity party and tells extended family lies and that we don't come around as if she has no fault in it or that it is a two-way road when it comes to visiting each other. I don't think she has ever been happy for us and or is genuine to our son or us. She comes off very phony. She has her oldest son ex-wife on her Facebook, her son (not related) and his girlfriend but not her ”own” grandson. Which I find hurtful and mean of her and to not consider his feelings is cruel. The ex-daughter in law is now remarried, and before she was divorced from my brother in law, they didn't like each other nor have a relationship. It was more cordial than anything. So I feel if she can't claim our son or acknowledge him much why should we let her know or be involved in our family unit or that we are expecting another child. Am I wrong for feeling this way? There is a lot more, but it will take too long to explain her hateful, mean behavior.