It sounds like you are in a situation where you need to let the things out that are bothering you but you are not ready for a confrontation with your mother.

Have you considered writing a letter to your mother? Even if you shred it immediately after you finish it may help just to let those things out. It could also give you an idea of exactly what you would say when you are able to discuss it with her. There is a good chance that she will react just how you explained so until you feel that you can handle that maybe it is best not to talk with her about it.

I wish you the best