So I play the goody good kind of guy that will help others just for the satisfaction of doing a good thing. Well... not exactly but you know what i mean.

So i visited Gomorra. I walked around, pvssyd with few people. I got laid with this beautiful hoker. She was so nice that she offered 'that' 'on the house'. When we were lying in her bed afterward she told me about this guy Cachino. Now I've been places, I've seen things, but this guy was just beyond sick. I've decided this had to stop. I had to stop him.

After I've done some research i 'found' his journal. In the mean time I also found that all Omertas are all sick and should be wiped if the New Vegas should become a safe and uncorrupted place. But I've decided that i should stop them step by step. I brought the Cachino's journal to his bosses - why should i get my hands dirty if others are so willing to do it for me.

Now that he was gone from the picture I've decided that i will help this unfortunate lady that actually love someone out there in the wastes. I've arranged her escape and reunited her with her love. Now i know it will be hard to find quality and free service but I'm just nice like that. Now that everything has been taken care of, it is time to take care of Omertas.

Since i gained their trust by revealing Cachino's treason it should be easy. I accept their job and plotted their demise. BAM! Now all i can do is just deliver the resources they need and that's it. Nothing. No way stop them. All i can do is to put few bullets in each of them but that's not the way i play, not the way it should be done, and the consequences are quite sever. What do i do?

Warning: if you let Cachico be killed by the bosses you might screw up
the NCR For the Republic quest. I had him killed and could no longer
gather evidence for the NCR to bring the Omerta bosses down. I think
it's a bug, but in any case I effed up the quest and found out 5 hours
later...

That's exactly where i am now. I've got Cachino killed long time ago now I'm back there with "For the Republic" quest with great WTF over my head.

Because really. I understand that taking down those bosses would require siding with sick psycho, but there was no warning that if i get rid of this sick psycho i would end up unable to get rid of them. Now when i type it is reasonable and that i should go there and shoot them out. But then i get bad reputation in the Strip and fail the quests.

Have you tried finding Troike and trying to talk to him about the guns?
That might somehow trigger the confrontation with Big Sal and Nero but I'm not sure if that's possible with Cachino already dead.

You might also try sniping Big Sal and Nero while hidden and maybe avoid Strip infamy.
Otherwise, you might just have to take the rep loss and try to make it up with other side quests around the Strip.

Wait... This is a long shot, but isn't there another copy of Cachico's journal in his room?

You're right.
I wonder though, if the game considers it the same one as you pickpocket from him or not?

You won't get strip infamy for killing Bil Sal and Nero, or any of the Omertas. They are a separate faction. I completely wiped out the Omertas in one playthrough and didn't gain any strip infamy, though I did become vilified with the Omertas.

My guess is it's not there anymore. And even if, it's related to the quest I've already finished.

I found something in big boss's safe. There was this letter that called Troike names and something. Can't really remember now. But when i brought this to him, he was not interested. All he wanted to know is when will i bring the stolen guns. Now i call him names too.

Hmmm.
Now that you mention it, on my first play through I sort of went nuts on the White Glove Society and only lost rep with them (straight to Wild Child) and not out on the Strip.

I think I lost Strip reputation when taking out the bosses but now I'm not sure anymore.

So anyway... the conclusion is that if you kill Cachino/get him killed the quests are broken? Shouldn't it get reported? I mean.. i don't think it is the way it should be.

Have you went back and talked to the quest giver?
I was stuck somewhere along the NCR quest line due to killing an informant.
I was told I had to had to 'lie' about it.
When I got back to the chick I had an option to 'lie' about the quest, and say the informant was fine, and nothing else needed looking into.
In fact they were all dead...

I don't remember what part though. I am sure it was with Cachino, but I think it was. I was tired of looking for the fools room so I 'popped' him in the back of the head while no one was looking.