MIL is ridiculous

Y’all sometimes ai just want to go off my rocker and lose it with this woman. I get so irritated. Any time we ask a favor ( very rarely) my in laws (specifically MIL) make it so difficult. I have a training I have to go to the next few days for work and over a week ago asked if my BIL (just recently turned 18) could come up friday to watch my girls even though he is technically an adult and of course can say yes he won’t because he does whatever his mom says and I have yet to get an answer at 2 days away. This is every single time. They always complain we never see them but they never make an effort to see us and we are usually down there atleast once a month ( they live an hour and a half away and if BIL comes we pick him up and take him home). She tried to demand a DNA on my child before, she has purposely said numerous hurtful things and tried to embarrass me and singles me out and says things on purpose to embarrass me and tries to manipulate my husband into making him feel bad. She’s gotten so petty so say I can’t drink certain drinks at her house but everyone else an and so on. One of these days... I’m tellin’ ya