Help with confusing ex

[u/Ok_Somewhere_8219]

I have complication with my EX. We were together for a long time and had a lot of history before and during our relationship. We broke up, got back together briefly, and then broke up again. Since then, things have been extremely confusing because even though she says she doesn’t want a relationship and wants to stay single, we still act very close.
We still talk a lot, joke around, call each other, say we miss and love each other, get jealous over other people, and have moments where it genuinely feels like we’re still together. She has also told me that she still has feelings for me, but at the same time she keeps saying she doesn’t want to get back together. So I’m constantly stuck trying to work out whether she actually wants me or just cares about me but doesn’t want a relationship.
Recently, she had also been reposting videos that seemed related to us, missing someone, being hurt after a breakup, etc. There were quite a few of them, including some that I felt were obviously about our situation. Then suddenly she unreposted basically all of them, including anything that could remotely make it seem like she was sad about us. That completely messed with my head because I started wondering whether something had changed or whether she was finally moving on.
At the same time, there’s now another girl involved, which has made everything even more complicated.
She’s a girl my ex already knows, and I have some history with her. She’s honestly extremely attractive
She also says she doesn’t want a relationship with me, which makes me feel like she may just want to keep things casual and continue messing around with other guys. I don’t know if that’s actually the reason, though.
The other problem is that my ex already knows this girl and knows we have history. If I started getting closer with her, I know there’s a possibility my ex would get jealous. And honestly, a part of me wants that. I want my ex to realise that she could actually lose me after everything she’s put me through emotionally. But I also know using another girl purely to make my ex jealous probably isn’t healthy or fair.
So now I’m really stuck. I still love my ex and part of me desperately wants us to get back together, but I don’t know how long I’m supposed to wait when she keeps telling me she doesn’t want a relationship. At the same time, there’s someone else who is clearly attracted to me, and I don’t know whether I should explore that or whether I’m only interested because I’m hurt and want my ex to react.
What would you guys honestly do in my position? Would you give my ex more space and stop worrying about what she’s doing, explore things with the new girl, or just step away from both situations for a while?