Let him be an outside cat. Buy him a little bed and give him table scraps. We feed stray cats at my job with our leftovers. Everyone pitches in an brings stuff. I would rescue every available cat if that were possible. Everyone reaches a point where it isn't responsible to take in more. Being a kind-hearted rescuer is often a heartache as well. I have 10, but that is what I have space and funds for. You'll have my full support whatever you decide is best.