Ok so i was minding my own business, then that Indian guy decides to attack me, i struggle at the beginning but then manage to kick his ass. I propose we make peace and i get 2 of his cities in exchange. Then all of the sudden Persia and that fat guy Sulian decide to declare war on me, and soon the rest of the world follows. WTH? HE attacked me, not the other way around, why is this happening? I hadn't been aggressive before this happened i only annexed one City State that was militaristic but they had no allies. Is this just dumb AI?
It's helpful to know what level you are playing on. Anyhow, I'll mention some of my experiences as I stepped along the difficulty path from King (easy) through Emperor (a bit harder) to Immortal (much harder ..at least for me

). My experiences have been enhanced by reading here and also by studing Sulla's detailed walkthoughs.
Anyhow, from my experiences, a primary reason for these piggybacked AI civ DOW's is that you don't have enough army. There seem to be certain minimal levels of troops that need to be maintained when compared to number of cities owned. ie..REXing or ICSing without at least a few military units and especially if near other AI's borders is a recipe for piggybacked DOW's and often the quick loss that results if too many AI units can flood your lands before you're prepared.
Of course, I presume that the AI civs also make POC and POS with each other, just like they may do in cooperation with you. This would contribute to the piggybacked DOW effect here.
What I think happened in your game is that the two civs Ghandi gave you pushed you below a threshhold for cities/army and now the AI's (who don't seem to be pleased by your expansion anyhow) think that you're too weak to defend everything. When they see easy pickings, they go after it.
Is your game lost now? It may depend on level (higher level means more enemy troops and with higher tech levels) and it may depend on how easily the AI's can stream units into your lands. Your survival will also depend on how well you can defend yourself. Maybe you can set up killing fields for the AI units, sending a couple dozen to their graves as you lose very little and prepare more troops. Then maybe you can counter attack or maybe some AI's just get sick of losing units and sue for peace.
As for Ghandi, he can become warlike when he thinks that you're a warmonger and "picking on the weak". Ghandi and some (maybe all) other leaders can get sometimes get quite angry the first time that you raze a city.
I almost NEVER attack a city-state for any reason unless they are allied with an enemy AND actively attacking me OR are in the path of attack to my enemy and allied with him. I MUCH prefer to ally with any CS, rather than to attack it, and even if they are military they can be useful and performing tasks for them can build up favor and make maintaining alliance less costly. Liberating a CS that has been taken by a warmongering enemy AI also makes that CS allies for a long time.
Anyhow...in summary, you probably need to have a somewhat larger army. Perhaps replay the game from an autosave or two to try.
Just my experiences .. neilkaz ..