New to this site...help!

Hello. I have 3 pitbulls, one female, one male, and their male offspring. and one boston terrier. They are 6 (boston terrier), 5 (female blue nose), 4 (103 lb mix pitbull) and 18 mth blue/mix. Before the puppies, I never had any problem with any aggression or prey drive. As soon as those puppies were born though, I noticed the dad became very protective of the female. He has proggressively become more and more aggressive with outside dogs. He doesnt attack unless he is attacked first but then he wont let go. There is nothing I can do to make him release his bite. Ive learned to walk with a stick just in case his muzzle comes off but it sucks to be afraid of what im going to run into during a walk.

I rent an apartment from my mom and she has cats in the hallway. Ive taken precautions so that there are no accidents but the other night a cat was hiding behind a door and i didnt see him. Before i knew it, the cat came out hissing and scratching, scratched my dog and that was it. the cat died. So now, she wants me to get rid of him or put him to sleep. Im going to get him fixed asap. just waiting for my appointment date. and also gonna get him some more training. But in the mean time, aside from making sure he is muzzled, is there anything i can do to get him to not be so focused on the cats? cuz even with the muzzle, i see his body language as soon as he sees one of them in the hallway. I dont want another accident. Id probably be asked to leave.

New to this site...help!