Sounds like your grandparents are very abusive and your mother suffered low esteem and carried on the abuse, just learned it from them. Blaming you for being the cause is a way of avoiding their own part in all the family dynamics.

They probably truly don't understand how college is an escape from their lifestyle not them. They might see your reaching for a better life as criticism of them not just a desire for a better life with more opportunities.

Understanding their point of view doesn't migate the pain you must feel. if you have a T talk about this with him/her or find someone you can talk to about this cause you shouldn't have to deal with this alone.