Am i reading the signs wrong with my ex? LONG QUESTION!?

i went out with kirk for 8 months since november of last year, and since we broke up a few months back i've always felt something towards him. but when i tried to get back with him a while ago ( i realsied i'd made a mive mistake) he told me i'd hurt him too much by breaking up with him as he didn't expect it. he said we should go our seperate ways. so, i took nothing to do with him, and this guy Jon asked me out. in a desperation to try and move on from Kirk, i agreed to go out with him, and as time went on i'd notice Kirk looking at me and i'd overheard his older brother telling him not to worry about things. but anyway, me and Jon were doing really good, and after going out for 6 days, he went out with his friends. the next day, i went to his house - things were fine. but he then changed the way he was on monday, and he admitted he still liked his ex. i was fine with this, we'd only been going out 8 days by this point. but then, tuesday morning in work, i found out he had slept with his ex on sunday night. stress gives me a headache, and i ended up having a blinding headache on tuesday night, and by wednesday it was still there. i found t-shirts belonging to Kirk and told him about this on Yahoo Messenger and we got talking. he then offered advice for my sore head, and he knows me too well - asked what was upsetting me, as i get a sore head when i'm upset. i told him about Jon and he was annoyed by the whole thing - and last night (thursday night) he popped up and asked if i still felt unwell. we got talking again, this time about his mother. i feel nothing for Jon, but the feelings for Kirk are coming back and i'm scared he doesn't feel the same way. PLEASE help me!?