I know too well the emotional trauma you are dealing with and the rough road you have ahead of you. However, the first thing that I would advise is to stop trying to make sense of irrational and illogical actions of others. It will never make sense!! Secondly, start as soon as possible to placing your focus on you and the future. Do not dwell on his actions, you have no control over what he does or says. Do NOT look at his actions as a reflection of you, because they are not!

I agree with cleigh, read her posts she knows what she is talking about.
Yes it will be a hard road. But know you will be a stronger and better person for it in the other side. It is journey full of many opportunities, good and bad. We are all here when you need us. Be strong!

I had the exact same thing happen to me. Same amount of years married. Came home one day & He had gone that day to rent an apartment with a woman he met at the gym in the early morning. I was in shock! He had texted me "I love you!" Five times that day saying he would be late. He was never late! And we own a business, so I always knew where he was. Except, he was a VERY early riser, and always went to the gym BY 5 a.m. Well, seems he had stopped the gym awhile before & was doing his calesthetics in a hotel room at 5! So, I asked him to leave immediately & our 17 yr marriage was over in 15 min! I opened my own business in the meantime & yet still had to see & communicate with him bcz of our other business. He synced his phone at work one day not long after we split, and when I was online going through photos one day that popped up from both our phones, all of her "nudies" that she'd been sending him popped up! This woman had just divorced her husband for cheating & ran from another state back to our state & she's a devout Mormon & still attends church 3 hours every Sunday. He tried to tell me how "good" she was when I had choice words for her. I guess bcz she doesn't drink coffee?!!! Ugh! Anyway, I felt your pain in your post deep in my heart. This man was my best friend, too, and I saw where he posted (when we were still together Christmas 2015) on her site "I've met my BFF!" The love of his life! He told me THEY pray for me....bcz of my pain & sadness. LOL it's like an SNL skit, right? Cleigh is 100% RIGHT! If you wait to FEEL like doing it, you never will. You just have to say every single time he pops into your head, "No! This is MY life & I only get one go around! I'm a person separate from him! Who was I before we ever met? I'm still that person. I need to get my eyes on ME. And not live in the past....yesterday is gone. And not live in the future....tomorrow has t happened yet! And who I am is not dependent on WHO I'm with, or IF I'm with anyone!" Listen, I'm stuck in a town where I have no family. My immediate family is all gone. Parents, brother. I'm not old. My sister lives far away. I only have a few acquaintances here. It gets very lonely....but you know what? It was a YEAR yesterday, and I made sure to go through every holiday alone. I did it deliberately. My brother was killed very tragically many years ago & I said to myself the day he left, "If I can live through THAT, this will be a cakewalk!!!" Now I see and talk to him daily. We're not divorced bcz of business ties ups, but he told me one day she no longer wants to get married. I told him it was none of my business. Sucks to be him! I had to learn to put myself first & get angry instead of sad. The sadness & looking at things as I "thought" they were is what was hanging me up. When I looked at the truth of how things were....I did it all & he just sucked the life out of me both physically & monetarily! He couldn't even get a phone when I met him! His entire family said as much the day they found out what he did. He thought this woman had $, I guess, and it turns out she cleans houses for a living. He's batting 100 so far! I have been falling in LIKE with myself again & I've come to realize that all the "I love you's, and constant cards & notes by the coffee pit daily," were just to keep me off track so that I would continue to trust him & never question his commitment, nor therefore, his whereabouts. Seems there are 1,000's just like him out there. Like the song says, "I can see clearly now, the rain has gone...". You will, too. Just hang in there & tell yourself, like Scarlett O'Hara, "I won't think about that today....I'll think about it tomorrow, after all, tomorrow is another day!" Think of who you were BEFORE meeting him & know that you are that same individual. YOU are still you! Get that person back. Blank out the in between. And only watch comedies like Mary Tyler Moore or songs by Cher @Do you believe in Life after love!" Don't wallow in self-pity. You're every bit as important as he is & HE will be the one who regrets his decision one day. Mine has already admitted that to me. In fact, I've saved a lot of his texts to show his BFF should I ever decide to. Right now I just say, "Meh...."let it go!" Move on!!!! Just move along! Laugh when u don't feel like it. Do it til it becomes real. Just do it! Don't wait to FEEL like it.