I guess what I'm not clear on is how much time is Gizzy in the crate? Do you put Forest in another room and let Gizzy have livingroom to run around to burn off some energy in exercise? Do you play actively with him, using something like a teaser toy? Give him lots of loving? I know when he sees Forest he's stimulated to spray, and I know in your small apartment there isn't much room for juggling cats in the kind of situation you've got. Hissing a lot as you reported Gizzy doing in your previous posts in July is always a sign of unhappiness, annoyance or frustration. It will be a difficult decision to make whether to surrender him or not that's for sure. I don't envy the position you're in, but I'm sure you and your bf will come to a decision that will be the best for Forest, Gizzy and yourselves. All the best!
"We humans are indeed fortunate if we happen to be chosen to be owned by a cat." -- Anonymous