Yesterday I had to move my 14 year old cat in with my girlfriend and I. He had been living with my parents and their golden retriever since I was a boy. My girlfriend has 2 cats that are 1 year old.

It has been hard getting the cats to get along, and been even harder watching him. He is an old boy and I am worried that he will not be happy here. It is only going to be for about a month, or until my parents can find a house to live in.

We have to share a single cat box, for we cannot afford to get another one. I am trying to always show him love, but am really worried about him. My girlfrend doesn't want me to single him out and give him more attention then the others. I just want the fighting between all of them to stop. Thank you

He is too old to have to deal with two young cats. Can you keep him away from them in a bedroom?

Litter boxes don't cost that much, or use a cardboard box that you've cut down. Put a layer of newspaper and a plastic garbage bag under it to catch any moisture that seeps through (and keep the litter clean!).

Your cat is an old man at this point and probably doesn't want to put up with a couple of kids.
You may have no choice but to single him out,
His own space, his own box, and plenty of TLC.
He has gone through a big change in moving, one of my cats literally pulled about 3/4 of her own fur out once after a move. It took her a little while to adjust to her new surroundings, but she didn't have new friends to adjust to, just a new house, but that was upsetting enough to her.
And if they are fighting you risk a bite that could result in an abcess, at his age he doesn't need an injury that may lead to a nasty infection.
You also could get some catitude, undesired behaviors because he is frustrated and unsettled.
I think keeping him away from the younger cats while he is there is a good idea.

Unfortunietly we have no choice to keep them together for about another 2 weeks. They got into a big fight last night, both seem to be OK.

My cat (the older one) has been moving around a lot, and seems to adjust OK to it's new surroundings, he has just never had another cat in the picture.

This has just been really hard dealing with all the fighting and hissing.

We keep them separated now whenever we leave so they can all rest and calm down.