Resource Guarding 4 month old

Hi there,

I have a 4 month old basset/aussie female mix who I adopted at 10 weeks. We're doing great with potty training, commands, etc. However her resource guarding has crossed into concerning territory for me.

I have two male 5 year old cats. They can definitely be rude and entitled in the way cats are sometimes. They used to steal food and things from our senior dog, who passed away in June.

I do feed the cats upstairs and the puppy downstairs so their meals are nowhere near each other.

When they first started attempting to do the food stealing with my puppy, she set a healthy boundary by barking at them. I thought that was fine. However, she seems to be getting more and more defensive. If she knows there are treats out, and the cats are simply existing in the room, she'll chase them out and bark. Today while we were working on commands, my cat passed by and she snapped and attempted to bite him. Later, when she was sleeping on my lap on the couch, the same cat jumped on the couch and she woke up and attempted to bite him again.

Immediately after that, I felt so tense and put her in her crate so that I could diffuse the situation and I could calm down myself. I'm just so scared and I can't stop crying. I left a message for a trainer but I'm so scared and I don't know if I can handle 10+ years of constant tension in the house. Our house isn't really set up in a way where keeping them separate forever would work meaningfully.