I'd consider that to be sexual abuse. It's not the form we hear about all the time because we've only had the internet for...how long? I didn't even have e-mail when I started my job! But these f*ckheads are out there grooming young people. Standard forms of sexual abuse don't require contact (though that is what we commonly refer to as abuse), but it includes forcing a kid to watch, getting off on watching a kid, etc. And if he was threatening suicide to a young kid, that's pretty controlling and manipulative and hard for a kid to understand or know how to respond to. Those are some major threats. At the very least it is horrible exploitation but I don't think it's too gray to be considered sexual abuse with the grooming, the acts involved, and the threats used...sounds like coercion into his personal child porn. Yes, sexual abuse.
I can understand taking your time. Probably talk to your therapist or psychiatrist first. As for PTSD, they'd be the ones to diagnose. But you deserve support with this no matter what the "diagnosis." It's just hard stuff and I'm sorry for what you've been through.