That your neighbor likely forgot and it wasn’t malicious, that you had to leave for several days yet still let your cat have access to the outdoors, and all the other details.

I can tell you’re grieving from multiple things here and you’re wounded. You have trauma and are acting irrationally. You are ruining your neighbor’s life. Please, PLEASE make this right if you still have time before he’s homeless and get therapy for yourself if you haven’t yet. I speak from experience. Please get help and don’t let your neighbor take the fall for this.