Monster in law

I find my husband's mom to be extremely annoying to me. I'm currently 15weeks pregnant she doesn't acknowledge me at times, It's like she does petty childish things that just sparks a fire inside of me, I keep quite but I do voice my opinions and concerns to my husband.she shows plenty of favoritism, and since my daughter isn't her biological grand daughter she doesn't even acknowledge her when she says hi,and it's starting to trickle down to the children trying to mistreat her. She may be the youngest and only girl but that's no reason to act that way towards a four year Old. Her own biological grandson she has no relationship with and that bothers me . Today I need suggestions before I explode. My solution is to ignore her and cut her out my life. HELP