Tips on beating Attilla on deity

So I usually dont play deity but I saw a nice save on the reddit group and decided to give it a spin
Its a deity standard pace small pangea map as the zulus

http://imgur.com/fdaghKm
This is the start so I settled beside both mt. kilimanjaro and KSM so only 3 cities
I went liberty because I figured I would start warmongering around the time of Impi and have a decently sized empire
However what I didnt expect is Attila to be my immediate neighbour, Ive been fighting him for the past 100 turns and am now starting to really fall behind in tech to the 2 runaway civs on the other side of the continent

Currently I am in the Renaissance era just trying to defend his endless stream of muskets and trebuchets. I have a decent sized army of 5 xbows and like 9 Impis which I am spamming out from the Kilimanjaro city. I am by no means losing units or getting sieged but I simply cant fight through his endless spam to get to a city

There is two other people at war with him but are not really fighting, the mountains and terrain are set up in a manner where it is just me and him fighting on two sides of a long river surrounded by jungle.

Any advice as to how I can kill him off, at this point I dont even want to win, I just want to kick him out of the game. My current plan is to beeline rifleman and upgrade all of my Impis

You can beat Attila on deity if you defend yourself and manage to prevent Attila's units from attacking and conquering your cities. If you can defend yourself, you won't suffer from any warmonger penalties that other AIs could see against you and be patient for world intervention. Warmonger penalties cause by you taking away Attila's city states or even killing off Attila as a whole can get you into trouble with other AIs particularly in deity difficulty.