I think I'm falling for her again.
What makes you think that you are starting to fall for her again?
I can not really explain this feeling in words to be honest.
I think it's great that you've found someone that you like so much. It's important to make sure that she likes you before you ask her out, though, or that could lead to a real awkward situation.
I get it. But if I ask her out and she says no, I'll hook up with someone else and ask her to watch.
If you ask her out and she says no, it would be inappropriate of you to hook up with someone just to get back at her. It would be unfair to the person you're hooking up with. I think you should reconsider that plan.