My cat refuses to get out of reach

I'm at a loss, I currently have a 9 month old who is ENAMORED with my cat, and anyone who has or had had a 9 month old, knows they aren't the gentlest creatures. I'm a major beleiver in teaching your kids to respect and be gentle with animals, but I'm also understanding of the fact that a 9 month old has no idea what "gentle" means yet. So I do my best to just monitor their interactions and at the very least ensure my cat always has an escape, my son is closed off in a small baby proofed section of the living room when he isn't being held, my couch has a "fence" of pillows/blankets set up so my cat can still lay on the comfortable couch where he can't reach her, her cat tree, toys, litter box, food, and water, are all outside my sons "allowed" space. All of this goes to say my cat still chooses to lay on the floor right next to him. And then she gets pissed off and meows and pins her ears at him when he messes with her. I move him and her away from each other the best I can but there's only so much I can do when she is adamant about being as close to him as possible. She has snapped at him a couple times (without making contact) and has nipped him once (no blood, bruising, or even dents in his skin, just scared him) I don't want this to continue to escalate but litterally short of making my cat a prisoner in her own home and locking her in a room there's nothing else I can do. I'll put him in his playpen where he physically can't access her and she will jump into it to lay next to him. I don't want to get rid of my cat and I love her dearly but I don't know how to keep them both safe.