I'm rather shocked that she physically lays hands on you by grabbing your headset. I'd be down at HR with that one.
As for the event, you really can't slide over a direct confrontation any longer, and your reasons for why you didn't invite her will only make her determined to work around your objections.
Your only point here is to tell her she is unwelcome at your gathering. Anything else that you say will have no meaning to her at all.
Since she is using text messages and emails, as well as personal confrontation, you must use the same means. You need to text message, email AND prepare a short letter to hand to her. This is my suggestion:
1. Send an email, cc-ing someone else to whom you are close and to whom she is known (and using return receipt.) "SusieQ, you are specifically not invited to the gathering on XX evening. You will be turned away if you attempt to attend." Nothing more! No closing "regards," or "sincerely," or even a signature. She can see who it's from on the email.
2. Write a short note, signed, and physically hand it to her. Exact same language in the letter as the email However, as you hand it to her, you must state something short but direct such as "Susie Q, this concerns the gathering. I will not expect to see you there."
3. After you have delivered the note, send a text. "SusieQ, you have had a letter and an email from me regarding the gathering. Please do not come to my home."
I'm sorry...you should know that I have cut someone from my husband's family out due to his incessant use of racist language and name-calling, and that at my office two weeks ago, we terminated a new associate for language which was bigoted and racist (no final warning, no probation - just done) based on statements that this person made to me. I have zero tolerance. I applaud you for taking a stand as well.