So I'm absolutely not defending any actions of his assuming this is absolutely true(especially don't wanna defend him after that shit WW leaked script)
However there are two sides to every story.
Not trying to be a victim blamer or anything, but the devil's advocate position would be that clearly the couple had shit going on for a while. They were separated for a while, Joss wasn't working with Marvel after AoU, he gets divorced, starts working on JL, and then this letter comes out. And honestly, it just comes off as someone who wants to shame her ex husband as he's getting a bunch of attention for a major movie. Timing just seems off. They were separated for years, only finished the divorce last year, and NOW she decides to make this statement.
Plus the one line she says makes me believe that it is possible she's jealous of the attention he paid other people, not necessarily full on cheating. She stated that she didn't like the attention he gave to female coworkers, fans, and friends, and that he hid multiple affairs.
Obviously if he did cheat on her, that's just awful. That's just being an awful human being to a partner.
But just the way she came out with this at such an odd time, while also emphasizing the "emotional" relationships he had with others makes me believe that she's simply jealous of others attention from Joss, sexually or not.
The main thing that would prove her point is the letter that she said Joss wrote confirming the infidelity. Which -in my opinion- if you're going to slam a public figure who is the father of your children and claim he caused you PTSD(give me a break) and claim there is solid evidence he admitted it…...then why not post it.
She's not suing for damages due to her condition or anything. She's just making a blog post to drag him, for her children his family and everyone else to see.
I think it's an outlandish statement to say he "gave his wife PTSD". She makes it pretty clear in her post that she was uncomfortable with how he interacted with other women for years. I'm sorry, but that's on you if you decide to stay in a relationship for that long with somebody who you clearly don't trust to be around other women. And if he did indeed cheat, then she was absolutely right in her doubt in him. But I mean I can get PTSD because I was fired from work, or got in a car accident and now am too afraid to drive again. That's not on the employer for firing me, or the car for not braking in time and hitting a pole. That's my personal issue. Don't go making a blog post about how someones actions "gave you" PTSD when people suffer far more traumatic events and don't go blaming other because of how they react.