Water, You definitely took the bull by the horns. You titled your thread, "It's really over..." but it may not be. Up until now, he's been in total control of the sitch, including his threats of leaving if you didn't stop snooping. He had you right where he wanted you so he could keep on chowing down on his cake.
Kicking him out was a LRT (and it took a huge amount of courage!). I bet he didn't see that coming at all. Now you're in control. I wouldn't be surprised if he doesn't come back asking for a second chance. So, if he does, be prepared. Know what you want (such end the A, NO contact, transparency from him, counseling).
OW may think she has it made but that isn't true. If she was pursuing and pressuring him before, she won't stop now. And now he's under even more pressure because his fantasy life, as well as his home life, is disintegrating.
Don't let him tell you you're not acting like an adult. What bull. He's the one that's been lying and sneaking around. He may be pretty angry for awhile so keep calm and strong.
