I need guidance. NOW!!

So my best friend let’s just call him Jack for now. We’ve been close for so long. We tell each other stuff and we trust each other with everything. We’ve done stuff together as far as going all the way quite a lot. Over the past few weeks since my other friend spoke to him we’ve been the closest we’ve ever been. We get food together and we hug lots and just do really cute things in public now and we never used to. But I feel ready to tell him how I feel and it’s way overdue but I’m just not sure after today. My friends have all said he’s so in to you it’s obvious just go out already (I can get where they’re getting from - we do everything that consists of a relationship we’ve just never made it official). I’ve now started to FINNALY believe he liked me back. But there’s this other girl who has a massive crush on jack and she’s doing everything in her power to make me jealous and to get with me but unfortunately although I notice he’s reluctant at first he does engage with hugging her and holding her hand and stuff. Honestly she’s so horrible to me and I tell him about it all the time and he tells me that he doesn’t like her and yet I still feel as if he does (she is his ex after all). I’m supposed to be going to his on Saturday although I’m not talking to him at the moment because he’s had an extremely bad day and is in a bad mood and I’m worried now he might cancel. I know for a fact though he’s only gone all the way with me just to note. I was so confident in telling him how I was really felt on Saturday but seeing him and her together at lunch made me feel sick and now I don’t want to because I feel like it won’t make any difference. I want to say to him I can’t make you love me nor can I force anything and I won’t but I can’t keep doing this if she’s around because it really breaks me. If you want to be with her that’s fine I’ll walk away. But I just don’t know! WHAT DO I DO AHHH