It's been somewhat alluded to in comments etc. already, but if you are worried about this person turning up at your house unannounced then it might really help to have an ally. Both at the time, and knowing that you will have one in the lead-up to your party.
You haven't stated either way, but it is probably incredibly stressful trying to contain this situation alone while you are hosting, let alone the fear hanging over you beforehand of the possibility of it. Knowing that it will not be on you alone to handle it if it happens offers literal peace of mind. If she does turn up unannounced, it will be much easier to deal with it how others have recommended, if you are not also worrying about what onlookers will think, who they will "side with" or (heaven forbid) what happens if this awful person gets out of hand.
You don't need to tell all your guests or make a big thing about it, just don't keep this wholly to yourself. If one or two trusted coworkers are aware, or even just your partner, then in that moment you will know you can project calm, firm, detached distancing without needing to engage in justification or any opening for debate. You can shut that door and people watching will know it was right. If she escalates, there will be people other than just you who are ready to help you.
She probably won't turn up at all, maybe she'd enjoy knowing that you're worrying about the possibility idk. The main reason to have this in place is rather to soothe your fears in the lead-up, by cutting down on a load of social "what ifs". What if guests think I was too rude, what if she kicks off etc. Nobody should bear those worries alone and in the event you will have a whole house of potential allies.
So just get one or two of them on side now, just in case, then when she doesn't turn up after all you won't have wasted so much emotional energy stressing about the possibility beforehand because you will know you're not, and won't be alone in handling this. These kinds of people love to get others expending emotional energy over them in that way, that's probably as far as this will go, but in the worst case having others on your side in the event will allow you to do all the detached "professional" type handling which others have recommended with your head held high.
It will probably be fine, you will have a great party, just don't carry this worry alone.