How freakin scary. I went through this with Bella too. She got her jaw caught in her collar a few weeks after I got her and was trying frantically to get it off. I noticed it and grabbed her quickly, but it took a few minutes to maneuver it to get it off. She was OK thank goodness, but I never placed another collar on her again after the incident. She wears harnesses only, and occasionally will wear her collar depending on her outfit, but with supervision only.
I am so glad you were home to help your babies out. Get better soon Kemo. Hopefully he wasn't traumatized to bad by it all. I know my girl bounced right back after that, even though I didn't.