[dandanisaur]

Unfortunately, the 'rookie move' is a fair assumption. Even if there was a small possibility of conflict: Your IP is your company and these things should have been covered.

It's a sad lesson and an emotional mistake. You didn't owe the employer/managers anything and should have cut all ties to the company especially since these projects are somewhat related.

You are both good guys for wanting to help out and it sucks that things got twisted up. I hope things work out well and I wish you all the best.