It sounds as if your Mom needs lots of prayer if both you and your sister struggle with your relationship with her. She was a child with grew up with flaws, and it's hard if the parent is the difficult child in the relationship. I imagine there are triggering causes, and for those...compassion, if also frustration.
It's what we have a right to expect of our parents that can hurt, because sometimes they're not up to those expectations. If it's hard to feel respect, it is still necessary to live and act with some respect, even if the disappointment cuts and interactions are difficult. The act of respect can take different forms, even part of which can be reasonable avoidance of situations with her that are set up to fail and cause her to behave badly or you to feel miserable.
How that respect translates is up to you to assess, knowing your situation, which we don't.
Yes it's great you have a Mom. Mine died when I was 18, and my Dad just died. My Dad...was the best person. Couldn't ask for more.
I still miss my mother sometimes.
But when you are hurt by a mother's insensitivity and lack of emotional support, it's very easy for others to comment and even to advise, but it's a very personal hurt, Belle, and any words that any of us can say can't ease the acute hurt at those times. In the end I guess you decide to be a very different kind of parent. Perhaps she's teaching you the kind of Mom you always wish to be, by what she is unable to be. She misses out on a lot, poor thing, if she doesn't get how to share love with her children.