I need to breakup with my mother...

My mom and I have never had a great relationship, and I never quite knew why. Her coping skills, or lack of became very evident in the lay few years dealing with my fathers illness.  She is very irrational, more impatient than ever, she's negative and all around difficult to be around. She complains about her life and certain things in it, but then refuses to do anything to make it better. She cries all the time, and I feel like this is a way for her to manipulate situations in her favor. I've tired everything. I listened to her. I tried to help her. I tried to fix things for her. And finally I have taken all of the blame for her problems. She has convinced herself that I am her own personal bad guy, that I wake up in the morning planning a way to ruin her day. This is more her theme than ever before because I have decided not to put up with her bullshit. I've decided that my feelings matter and addressing them is important to me. For years anytime I try to bring up my feelings in. Regards to her or our relationship she accuses me of attacking her and throws a fit. My feelings go into a pile in the corner with the rest of my feelings for the past 15 years. I put my own feelings aside in order to have peaceful holidays, to spend time together as a family bc my dad is sick. 

And now I'm having a baby. It will be. A beautiful baby and my child is lucky enough to have grandparents in both sides alive. I want my child to have a relationship with all their grandparents, but I can no longer have a relationship with my mother. I cannot be her bad guy anymore, I cannot take the blame for her stress. I understand that she has had a rough few years, but I don't remember a time in my childhood when she kissed me, or told me she loved me, I feel that because of my constant need as a child for her love I have accepted that "dinners are better when you're not here" was because I was a horrible person, and not the other way around. It has taken a while, but I'm ready to move on. I will reach out to my father to be in the child's life, but I can't even imagine how my decision to be happy, to feel less guilt, to have less anxiety and tension at the mention of her name will affect my dad. He is an incredibly devoted husband, they are a team, just as me and my husband are. This is really hard.