How do I handle my SO's grandma?

My SO's grandma is very important to him and is like a second mom. When I met her she liked me a lot and always treated me so well. We had a good relationship. Then while I was giving birth I had her in the room because she was so excited about the baby. My contractions were getting so intense and I was about 6cm so I asked my sisters and her if I can just be alone with my husband for a while. (I felt like I was going to die and I was crying) After that, my sisters left no problem.

She gave a look like "How could you" and left. When the baby was born she never came back to the hospital and didnt see her until she was two months. All that time she told.me she would help out but got THAT pissed because I politely asked for some alone time. Now when I come over, she ignores me completely. Doesn't say hi, and isn't involved in my child's life at all. It hurts my feelings. I know she isn't obligated to babysit, i dont mind that. I just dont understand how she can let something that small interfere with her granddaughters life.

I've tried to say Hi and still smile at her but she ignores me completely. My mom said I should be extra nice to her and all that, but I've tried. I think if this woman is that old and immature, I dont need her in my child's life anyway. And maybe she doesn't truly love her.