Am i doing something awful?

Ok, so, i literally have absolutely no one i can talk to about this, so imma just put it out here if thats okay :')

basically, my boyfriend of 18 months and i broke up 3 weeks ago... and ever since then me and one of his close friends (lets call him P) have been hanging out
more than usual, and then last week he confessed that he liked me as more than a friend... we met up again today and we were flirting... so much like, tickle fighting for crying out loud, but later when he'd left he confessed he wanted to kiss me... and i said i kinda wanted him to too (he also said that he didn't because he didn't think i would want him to) But the thing is, idk why but i guess its an insecurity thing, but i seem to just automatically get attached to the first person that shows me any interest... which then makes it difficult to discern whether or not my feelings are genuine... i'm also pretty confused as to why he would show any interest in me :') not long ago at all he was kinda upset about being rejected by a girl that he had liked for a while and i consoled him and stuff - so i don't know if he's kind of 'rejection rebounding' me?

There's also the issue of my ex boyfriend - P is one of his closest friends and there only have been 3 weeks since we broke up. the thing is, it was a mutual break up and we decided it was best because the spark had just gone and it wasn't working out. but i mean, obviously i still love him - i'm not exactly going to get over him that quickly.. me and P haven't told ANYONE about this... (because it would probably crush my ex and pretty sure most of our friends would be like: "...what the actual **** are you playing at guys??" - i also feel like a huge hypocrite because one of my best friend found out that her (recently) ex boyfriend of over 3 years and one of her best friends were dating little under a week after they broke up and she is beyond ****ing devastated)

oh man i am a horrible person

idk what to do - i can't tell if i actually like P or if i'm just rebounding or just trying to distract myself from crumbling to pieces after breaking up with the best relationship i've ever had. and if P genuinely likes me and he's not rejection rebounding me, then i dont want to mess him around because thats awful too and i dont wanna ruin a good friendship because we are good friends and i always seem to mess up a lot of friendships because someone ends up having feelings for someone

i also dont know whether or not it's paranoia (probably) but i can't get it out of my head that the day that my ex and i broke up he told me that it was quite probable that P would try hit on me - but at the time i said that i would never do that to him nor did i like P that way (i also can't tell if i said that just to make him feel better - i couldn't exactly say, "wellll actually i probably would accept his advances should he make any")

So i can't stop thinking that maybe my ex put P up to this and this is some kind of cruel test to see if i was lying or if i'm just a horrible person in general

because i feel horrible - except when im with P - then when he leaves i just feel so guilty

I also spoke to my ex the other day and apparently he's had a few people make advances on him and he declined but they weren't one of my best friends and were just randomers

idk what to do - i dont know if im being used or if everything is genuine or whether i should just not do anything at all with P (i don't think id go any further than making out tbh, not this soon, but the principle is still there)

anyone got an opinion on this?? we're all 18 and part of the same 'friend tree'

(sorry this is so long!)

Don't date friends ever, and don't let your ex manipulate you in not hooking up with someone new. You are broken up, you can do whatever you want, you don't need to check in with him on how you haven't been with anyone. Your ex is a jackass, you don't need to be having those type of conversations with him. Go no contact.