Confused in this situation with ex friends

Hello everyone! I’d like to have good advice for this difficult situation! Also i’d like to say that this is not my native language. The theme is going to be about my confusion how to react when i met people who swindled me in many ways. So recently i met my “ex friends” (people who owe me money like 800$ and of course i wont get them back). I met them in my hometown at the shop. Nearby from their car my cousin was just drolling drunk for no reason. When those people went back to car “my debtor” pushed him down probably because he was blocking way to open car doors. I didnt see that moment but my friends did and actually i wanted to chase to those faggots but they drove home. Later on i met one of their friends in bar. When was the time to go home apparently he was waiting for me outside of a bar and wanted to fight, because i was complaining to his friends how miserable my debtor is but that could happen like 2 months ago in addition i was drunk and i’ve no memory from that. When the fight started i freakin froze and get confused because i had no fight experience i knew a bit what to do but i was completely insecure and scared to get punched just because some debts in uni was waiting for me couple of days later. So i decided to fall down and protect my head from max punches i could do. In the end that was probably my biggest humiliation ever been. Now i feel like i just want to destroy those people.. I also feel how strongly damaged my self-esteem is and i think it will be until the moment i prove those freaks that i can beat them down. Luckily just my forehead suffered a little bit and one side of eye a bit and now on this 3rd day after this accident my eye is almost fine. This situation totally made me think to start improve some fighting skills just at least to feel safe for unexpected situations like this and also return to gym which i have skipped for like 3 months. Problem also was that i was drunk pretty well and i couldnt do anything but in this case its very well if i would resist i wouldnt be able to finish my debts in uni. Nothing is over yet i guess. I’ve got many people who are really willing to teach a lesson to those miserable people who enjoy to humiliate, cheat and make other people to suffer. Actually im just wondering why i just didnt go to police but this is small Baltic state country where those punishments are not that high and many bullies stay without any sanctions. Needless to say that my debtor is a guy who is my exgirl’s sister’s boyfriend and we lived together for 5 months on last year until moment i figured how two-faced and miserable all those people are. What are your thoughts of this?

Thanks a lot for Your suggestions. You are truly right about most of the things. Thats what im doing this whole year - becoming better person. But this moment i have lost my balance in life because of this accident - i felt really humiliated. I feel like i have to find him and just beat him down then i will feel better.