Mama drama...why me? (looooong)

Brief background: My mother is 50, I'm 30. She is still married to my father who physically abused her until about 15 years ago when he figured out he could go to jail for his actions. She has been admittedly depressed off and on for several years since losing her mom to cancer 27 yrs. ago. She is very critical of me, my sister and my brother. Her major hobby is gossiping. She's also very materialistic and loves buying new things...cars, jewelry, clothes...then going 'down home' to show them off to her less fortunate siblings whom she was estranged from for most of my childhood. My mother and I have had a rocky relationship, with even the best of times marked by an underlying tension.

Now the current drama...my husband and I have just purchased our first home. This is a huge deal for us, he's an orphan and grew up impoverished in the foster care system. We feel really blessed, but vulnerable at the same time. We married very young (7 yrs ago) and came very close to a divorce 2 yrs ago. We've decided to have a houseblessing ceremony and invited only close family and friends, about 15 people. Thus the drama...my mother asked me for another invitation for her best friend. I didn't object. I’ve known this friend for years and want my mother to be happy. The next day she stops by with her friend and I give her the invitation, then my mother says "I need another invitation ____". This is a co-worker/friend that I've only met once when I stopped by mother's office. She said "You must be ______". I reached out my hand and said "Yes, and you are?" She smirked and said "_____", never bothering to shake my hand. Now why would I want to invite this person to my home? I told my mother I didn't have any more invitations. Two days later she leaves me a voicemail that she wants to invite another friend and she'll get the address for me. I stop by her house to tell her that this is a small intimate thing, not a party, and before I open my mouth she says she's inviting two of her brothers and a sister and their respective families. I said "No, I didn't send them an invitation, I don't have the room for that and I haven't seen them for well over a decade." She yells at me that they probably won't even come, but she wants me to invite them. In an amazing coincidence my uncle calls at that moment and she invites him in my face. I just left. I called the next day to tell her I didn't have the room, and my houseblessing is for CLOSE family and friends. She called back to say that if it's a houseblessing then it should be family before friends, but if it's a party then she'll just be in and out real quick so I can mingle with my friends."

I have been so happy over the past few months, now this. How did my special day get this horrible cloud over it? I told my husband that I don't really want to have it now. Why couldn't she just take her invitation and show up like everybody else? I feel like such an evil person right now. Logically I know that I didn't start this, but no matter what I'm the bad guy. She uninvited her best friend and told her I only wanted the people I originally invited there. I've definitely learned my lesson about inviting my mother to anything.

I forgot to add that my mother dislikes her house and has been trying unsuccessfully for years to get my father to move. I feel guilty, that by extension, my home is her chance to 'show off' a new house, and I'm denying her that. I know she's embarrassed that she had to uninvite people and feel guilty about that too.

Sorry so long, but I had to get this out. :(