How to beat someone in fight? what to do in this situation?

i live in Mexico, my name is Alex,i have a best friend named Cruz he's like my brother, he lives in my neighborhood, before some days a girl came to live in our neighbor named Alfonsa, and my friend Cruz like her too much he wanted to friendship her but Yesterday when i was going to cruz's home another guy named Alvarez was trying to flirt alfonsa and said something bad to her but she's innocent she ran away from there, then i get to the cruz's home and i told him everything and he was pissed off, then me and cruz get to Alvarez home, we told him if we saw you again in our street we will kick your ***, and fu*k you up, then he said abusive words too, he said i can beat you up but you guys are two and i am only one so we told him to call someone that can help you in fight (me,cruz,alvarez are 15) then alvarez's friend came, he is a bully he's 18 and too much stronger than us we want to kill him, he came and insulted us, said abusive words to us, he and Alvarez pushed us to the ground then we tried to fight back but failed (because he is stronger) then we called our 3 friends, 2 guys are 17 and one is 23 years old or something (of course they are more stronger than that bully jackass guy), our friends came and asked to the bully guy what happened and that bully guy then calmed down (because of our friends but our friends were trying to stop this fight with kindness) but he's clever he handled the situation, the argument was long enough in the end he said that don't tell bad words to Alvarez (to beat the conversation), finally we came to a deal that no one will fight each other or would say abusive words, our friends, alvarez and bully guy was gone, then me and cruz were talking about the fight on the street, suddenly the bully guy came again with alvarez and said bad words, bully guy had a knife in his hand, he said if i saw you both again i will beat you so bad with hockey and i will call my every friend, then alvarez and bully guy gone,we didn't tried to fight that time cause he had knife, and no we are not coward or afraid that's why we didn't told this to our families, we tried to call our friends with cell but no one picking our damn phone, that's sucks i think they are selfish, and look after one hour our another friend came we told everything to him and he said wow you are fighting for Alfonsa that girl's character is not good she's something like call girl she's not innocent and he said too many things that all are true, then cruz and me were both sad and shocked so the question is we fought for a girl who's not good and the bully guy and alvarez tries to beat us, what should we do in this situation and no one is agree to fight from our side!!! so do you guys think we should change our self's and fight them alone?