Why does my mother steadily make me feel guilty?

Why does my mother steadily make me feel guilty?  I seriously can't take it.  I feel like I'm on the edge of a nervous breakdown, and it scares me and I'm not sure what to do.  She's so jealous of my relationships with other people that she can't stand it so she acts out.  I don't know how to handle that.  While I'm laying in the bed playing games and arguing with my mother, my old dog pisses under my bed. WTF.  This is where I lost it and gave up. Screamed a little, took my meds, cleaned up the piss, put on hubbies tshirt and rescheduled our dinner with our friends, because I just can't do it today.   I can't do anything. The dog is shaking now and I feel bad.