Oh Junk, this is so sad. I'm so sorry that you went through that.
And, know that HE is the home wrecker, HE hurt his wife and children. He chose to groom, coerce and abuse a vulnerable patient.
I do understand that you feel guilty, but you have nothing to be guilty for. And, as you said above, lots of people actually do have feelings for their therapists, and come on to them etc. even if someone directly did that the therapist STILL has a moral obligation to keep the professional boundaries. I know you didn't come on to your T, but even if you had, he would still be the one at fault.
I hope that your new T will help you slowly work this through.
Hugs if you want them xxx