Am I overreacting ? Baby’s grandma

I do not co parent with my baby’s father at all we both agreed that it would be best if he wasn’t in his my baby’s life & for other personal reasons.

My baby’s grandma (his mom) claims to love her grandchild & wants to help me out long story short I took on a good job she agreed to help me every other weekend with the baby I’ve been at my new job for a month & has only helped me for 1 weekend she has a colostomy bag so the other times she couldn’t care for the baby she put that as an excuse. I understand her condition but she could’ve told me this since the beginning she claims that she’s unable to carry the baby because he’s too heavy & her bag might explode those are her exact words btw. Today I decided to completely cut her off I worked a mid shift today & literally 2 hours before my shift she told me she couldn’t take care of him because of her bag she told me to ask the baby’s uncle if he could watch I obviously did not feel comfortable with this & just hung up on her. I’m at work right now in tears because I had to leave my baby with a last minute babysitter I am thinking about going back to my fast food job only because they were very flexible with my schedule. Am I overreacting/selfish for wanting to cut her off? His dad doesn’t even live in the states & we ended on good terms