I'm 27 years old and I'm engaged... my fiancé is always putting me down... I have asked him to stop but he tells me I deserve it... before I moved up here with him I was taking care of my dying grandmother, after she passed I felt like everything is my fault for leaving her side... all because I believed what he said... the situation is getting worse... what do I do?

He tells you that you deserve it? It's an abusive relationship. Time to move on.

I do not think you need to carry on this relationship because his 'you deserve it' is not worth-digesting. Just move on.

Everyone here is going to say the same thing - leave someone who puts you down that way.
I want to ask you about leaving your dying grandmother's side... tell us more about that. The man is easy to dump, but any guilt you have needs to be addressed. Who took over her care? When did she die after you left? How old was she?

Since you asked specifically about your relationship, and not about the guilt you feel because of your grandmother, I will address your specific question.

What you do is leave. He's abusive. If not physically, at the very least emotionally. He's not worthy.

If you need help dealing with your guilt that would be a subject for another question, another thread. But the question at hand is what you should do about your relationship, and that answer is simple. You leave.

Whether you left your grandmother's side before or after, the guy is abusive. If you are so terrible why dies he want to marry you? My guess is so he can continue to abuse. ( your guilt would allow him to)
There is no reason any woman should stick around for more of that. You leave him and be glad you did.

Damn... thank you all for your responses... and to address some of your questions... I don't talk about my grandmothers death because the truth is it really does weigh very heavy on me... I can't believe that I made such a stupid decision... I seriously thought that he was different... someone I could treasure and he would do the same for me... but the truth is he attempts to isolate me from my family and wants me to be close to his... I thank you all so much for your caring words... and today I realized something... Its sad but the man who claimed to love me truly doesn't... and I thank you kind strangers for talking to me and helping me realize I'm really not the piece of he claims that I am