Issue with a friend

So, riddle me this:
I have a friend who is a lot like me. We get along wonderfully and I love her kids. Her husband and husband's side of the family is starting to get under my skin though.
She talks about how she never has any friends. I get that. I also don't have many friends that I can hang with because they all live so far away. So she has little girls that are just slightly younger than my three. I thought I finally found a good friend that I could hang out with here in my town. Boy am I starting to see that there will be some people I'll have to bitch slap to keep this friendship going.
First, her mother-in-law. For some stupid reason, she doesn't like me. I never did ANYTHING to this woman but adore her grandchildren and be a friend to her son and daughter-in-law but for some reason, she has a bone to pick with me and I'm about ready to put her in her place. She bitches to my friend that she spends too much time with me, that she never gets to see her grandkids anymore because she's always hanging out with me. FIRST, I see them maybe once a week. And SECOND, you have plenty of time to see your grandchildren! I'm not stopping you from that! My kids only see their grandparents 1-2 times a month! And it's not even for that long! Get off it! God!
Next, her husband. He seems to like me, we laugh and joke around when I'm around him. But when she wants to get out of the house for just a bit (sometimes as short as a half hour) he throws a hissy fit. Yesterday, she dropped me and my children off at the house. She was gone from the house for maybe 30 minutes and he calls all ticked off because she was taking forever. Seriously? You aren't working right now, and if you are a father, you should be able to handle your children without your wife holding your hand every step of the way. LET HER GET OUT AND BE AWAY FOR A FUCKING HALF HOUR! If we need to go grocery shopping, just let us go! I'm so sorry that you cannot handle being with your own children for a few hours. I'm so sorry that your children are getting in the way of you doing nothing. But if my husband pulled this bull crap on me and got on my crap about getting out of the house for a few hours with my friends, I would have to lay it out for him.
My poor friend has 4 children. They are 3 months old, 18 months old and 3 years old. She also has a son that is 7 that was shooken by his biological father when he was a baby and is now brain-damaged and needs a caregiver every second of every day. I would have lost my mind by now, but she has sacrificed her whole life for her son and her 3 daughters. The right thing to do would be to get her out of the house and let her just be her! We even took her son and my youngest daughter out grocery shopping once and he had a fit about that. I think it's bull shit, I think my friend needs to start standing up for herself and lay down the law because I'm sick of it. I like her husband, but I'm about ready to go rounds with him. This is starting to piss me off. Not only is this family trying to keep me from having a friend to relate too, they are stopping her from having ANY life. And that pisses me off more than anything. My vent for the day.