Alright so last night i took in a stray that may be a little under 8 weeks maybe younger that only had 3 legs and happens to be the runt out of the litter. It appears that the mother wants nothing to do with it since all it does is hiss and scratch at it every time it got near her or its siblings. I decided to take in the poor girl, but the only problem i have is i have a male cat who is a year old that may be too rough when it comes to interacting with her. They don't hiss at one another, but occasionally I'll break them apart whenever they do wrestle. He has been neutered since last december and i do plan on taking the newcomer to the vet within the next couple days. Keeping them seperated is hard to do since i live in a pretty small apartment. What actions should i take?