How do I handle my awful aunt on Thanksgiving?

Long story short, my aunt is a horrible person and I don't want her having any part of my life. Most of my family are the type of people who won't cut out family members "because they're family". So I have to see her a few times a year, mainly just major holidays. I haven't seen her since last Christmas and before that, I hadn't seen her since the previous Christmas, thankfully. But she'll be at Thanksgiving. For the last few years, my husband and I have been hosting a little get together with both our families and a couple friends once a year, but have never invited her. The first year, she asked me at Thanksgiving about why she wasn't invited to our gathering (she overheard other family talking about it) and I just played it off as "I didn't think you'd want to come because you aren't around a whole lot". I think she may be starting to get the hint that I don't like her, but she's pretty oblivious and thinks we're fine, and I'm trying to keep the peace and not start a bunch of drama for the rest of the family's sake, so I'm trying to play it cool and not just come out and tell her I can't stand her and don't invite her because I never want her stepping foot in my house. After I came up with that excuse that first year, she said she wants to come next time and I kinda just brushed her off. She's rude, immature, trashy, has a major attitude, thinks the world revolves around her, and has no filter. She has done and said some things that are absolutely unforgivable to me. She's like a child in the sense that she will blurt out her every thought and question, no matter how inappropriate or rude it is, and keep pressing it until she gets a response that pleases her. She's in her 40s but acts like a teenager (actually, that's an insult to teenagers. I'm sorry. But that's the best way I can describe her) Like, when I was a teenager, I thought she was the fun, cool aunt. Now that I'm an adult, I just realize how immature and horrible she is. I have a very strong feeling she's going to bring up our gathering on Thanksgiving (since we had our third one recently) and hound me about why she still has not been invited. I need help coming up with a response. I don't think well on my feet, so I need to rehearse this lol and I've been trying to come up with a response for like a week and I've got nothing. My husband hasn't been much help, even though he's better with words than I am. I thought about something like "we just wanted to keep it small" but she's going to be like "what's one more person". I'm stuck. I usually just try to avoid her on holidays, but she makes it impossible sometimes. Please help me deal with my dysfunctional family for the holidays!!! lol