A sad welcome but you are in good company here. Shock and hurt is normal. How could you know or even imagine this? Also - don't ask what you could-of-done or didn't-do-right. That's a rabbit hole with no bottom. What you thought was your life has turned out to be build upon a large amount of either deception, denial or lies and that's not your fault.

Now that you know some truths - breath. Allow a little time to mourn what happened to your relationship but start taking steps forward, even a small one each day.

Get some legal advice. If you're not ready to talk to someone yet, start a little online research into the laws and process for your jurisdiction. If you have kids, it's even more important to start thinking about their future.

Get some support, professional or from a close friend or family member. "Man up" is not the answer here. Just having someone willing to listen to you helps, even if they may not fully grasp the situation.

Start doing things for yourself so you can focus on healing. Whatever works, a hobby, social club, a little walking or jogging. Whatever you're into or always wanted to do.

It will be difficult living next door to 'the other woman' . I'd suggest taking the high road and avoid contact. I don't think it would help at this point.

Hang in there, it might seem like there's an impossible journey ahead of you but you can do it.
 

Thanks for the encouragement.  Sitting here alone with these thoughts is painful.
I am usually a pretty optimistic person but this sucks. All the emotions. Is no contact the way to go? She got her apartment yesterday. She will be here tomorrow to pack stuff up for her movers.