I'm so sorry this has happened to you. You must be shocked and devastated. I think this is probably the most shocking thing I've ever read on here a I actually gasped and clapped my hand to my mouth. I even hoped it might be a troll thread, it's that awful.
Don't minimise to yourself or anyone else the seriousness of what he has done. This is sexual assault and he knew what he was doing. The fact he pretended to be asleep when you stirred then carried on tells you he knew it was wrong, but didn't care.
Please report him to the police as he will do this to someone else. Hopefully the police can force the images to be destroyed.
I understand you not wanting to tell your kids the truth, but as teenage boys who will likely be looking at porn at some point in the future you don't want to risk them stumbling across these images! I would tell them that you found evidence he had taken indecent photographs of you without your consent. You don't need to give the rest of the details unless they are old enough for a talk about those specific actions and to reiterate how it's never ok AND you feel comfortable talking it through.
Definitely block him on the kids devices, unless they are his children he should not be contacting them. You certainly don't want his influence on their characters!
On yours, screenshot everything if he admits guilt etc. just in case he deletes it later. Block him so he cannot contact you. Don't give him the heads up about the police as this will give him chance to delete everything.
Find your anger and use it to push aside any shame - the only shame belongs to HIM. Don't let him get away with this.
Once again, I am so sorry this happened to you. You did not deserve it.