Three cats and the new fights the other 2 what do i do?

I have one female declawed cat who is 11. We have another male outdoor/indoor cat who is 5. I took in another stray but he is aggressive with the other cats. He is the worst with the female he will hunt her out and attack her even in her sleep. If they come near his door he fights them from under the door. When I hold him to smell the female cat he turns his head while she hisses at him. He is GREAT with people and children. I feel bad because he spends most days alone confined to rooming around our third floor lower level. He has loads of space but cries at night to be with us.