Should I Cut Ties?

My mother and I have NEVER had a good relationship. She signed her rights away on my sister and me when I was 2 and she was 6 weeks old. My dad raised us and still let her see us (I think her reason was she didn’t want to pay child support) but every time she came around she would cuss my dad out and end up getting us all upset and crying. Sometimes cops were called because she was so riled up. On one occasion she called child services on my dad and stepmom and said they were sexually abusing us (sad attempt to try to get custody back) which was complete BS. My dad and stepmom gave us an amazing childhood, my dad worked 2 jobs (factory and flipping houses) and my stepmom was a paramedic. Christmases were always huge, we had a couple horses they would ride with us, and I dont ever remember seeing them fight or argue. I remember them cleaning together and laughing all the time. She also not once introduced me as a stepdaughter. She always said “This is my oldest daughter” when introducing me and it always made me happy. Anyway, when I was going to have my first child, my mom insisted that she be in the room (like she has tried to do for all my kids) and made a huge deal over the fact I didn’t want her to be in there. I went thru a lot without her so why would I want/need her there when i give birth? I didn’t. So for the past 8 years I’ve basically just tried to be civil when I do see her but I’m just done. I have 5 children and not once has she ever offered to help me in anyway. She helps my older sister (she wasn’t my dads daughter, mom already had her when they met) all the time but never me or my little sister. She’s always getting offended or not taking responsibility for anything she does. Anyway on thanksgiving she came over unannounced like always, which I hate because i have 5 kids and my house isn’t always tidy and spotless so I like a little heads up before people come by, and started mouthing at my husband saying he didn’t care about me and pointing in his face (I’m having some PPD, my daughter was born Nov 6th) which upset me even more, and then didn’t bother to tell me that my niece has lice until after she left. (She called DCS on my older sister and ended up with custody of my niece) She’s ALWAYS getting someone sick because she doesn’t mention it until you’ve already been around her and when you get mad at her for it she acts like you’re being so disrespectful to her. Like it’s not inconsiderate of her to come around other people’s kids while sick or with lice. I’m just done trying to have any kind of relationship with her. I want to block her number and just be done but she’s SUCH a crap starter out of spite I don’t want to deal with that either!