Why oh WHY didn't he tell me all of this last DDay
Same reason so many, if not all, WS's do the TT routine to the death or near death of their marriages.
My wife didn't tell me the truth, or the counselors IC or MC, until 6 months of counseling had passed, until she'd put me through Hell with the lies that didn't make any sense, and until she'd insisted she was "...I am telling you the truth" and then firmly saying "you just can't handle the truth, you can't handle it".
Me going nuts just trying to reconcile the fact that what was being said didn't make any fucking sense at all....perhaps to a counselor, but not to someone who knew his wife and remembered a lot about the past and recognized it just didn't add up.
Then, suddenly, after 6 months of this torture, breaking down, and dropping to her knees in our yard in tears, when I'm just about to drive off to work, and without any preamble practically vomiting out the truth, the real truth, not the truth as she wanted it to be.
What you are experiencing is the revelation, PAINFULLY slowly, not of an affair, but of how broken your spouse really is emotionally. It takes months, if not years, to work on this.
My wife insisted there was no sex at our house, no sex with our kids around, etc, etc, etc. When the reality is that she'd put the kids in front of the TV, walked the guy down the short hallway, and had sex with him in our bed with the kids only 30 feet away, blow jobs in the garage with the kids playing in the yard, as well as getting drunk and giving him a blow job in a public park near the center of town out in the open near some picnicking tables, kissing him with the kids around, and taking all the kids to meet him. Drinking with him and the kids present, driving home buzzed, drinking to get in the mood for sex during the day, and using MJ to get stoned when she couldn't handle what she was doing, before drinking in the afternoon to do more of the same.
All for a guy who was a stand-up citizen, stable businessman, hard working family guy, NOT!
For a guy who was a serial cheater on his wife, who didn't pay his bills, who didn't pay attention to his kids, who didn't do his work, who would say anything to get what he wanted, and who was so stupid that he thought the two of them should run away together (never figured out if they were taking the kids with them or not).
Within 4 weeks of this vomiting up the truth, my wife began to truly engage in MC for real, she was diagnosed with alcoholism, she entered AA, she dropped multiple friends who she had been engaging in secret drug use with (and who functioned as her suppliers for her Marijuana...not the drug to be using if you have depression), and she confronted the reality in her life of her being codependent to a severe degree. She exposed the sexual abuse as a child, she exposed the rapes as an adult, she exposed the truth about her first marriage, and she exposed the truth about her life before she met me and the degree that her actions went to in order to gain approval from men. All of which I had to face as well.
I think, in retrospect, that the reason the second year of MC is so hard, is that you finally get to work on the truth as it is, not as the parties want it to be.