A small update on my life. I really need someone to help me out,mentally.

While she was in Serbia, I started going out again,flirting with girls,ended up in a small "relationship" with a girl for about a week (she wasn't from here and had to leave and I didn't want a distance relationship) and the girl wasn't even on my mind.

She's back again and I am alone again. It seems like I'm now in love with her 120% but at the same time hate everything about her. Probably has something to do with the fact that the other girl isn't here for me and I feel so lonely.

Every time I see her, my heart jumps, her reaction is unknown because she hasn't seen me yet but it's probably negative, she hasn't texted me since she left.

I think my problem is that I thought that with these steps, I will be healed and was surprised that it worked so fast, but I guess I was just pushing away my feelings for her..

Someone please help me out,clear my mind. I know that I CAN'T be with her again but it's so hard for me right now. I'm trying to be strong but I become more and more desperate...

The best thing you can do is to avoid jumping into another relationship. The new girl was a distraction and once she was not there your mind went back to its original worries. You need to deal with this yourself and heal and get over her before getting into another relationship. You should accept that you can't just replace her with someone else overnight.
Instead of trying to get into a new relationship you can meet with friends or even go on a new date but with the intention of having fun and getting to know someone knew. You don't have to expect too much or try to over analyse things. Just let things take their own course. But for all that to happen you need to give your life that push again, don't be stuck in the past, what's done is done, there are more loads things to come your way and if you keep looking back you might miss out on some great stuff. Keep that in mind and take it one day at a time.