He's suggesting that my W left me because she had the courage that I didn't have.
There is absolutely NOTHING "courageous" about a spouse committing adultery on another spouse. It's ABUSE. It's soul destroying to both the wayward spouse and the betrayed spouse.
Courage might be demanding things change and being so bold as to separate or even file for divorce as a direct action or ultimatum that the marriage needs to be worked on and improved or else that spouse is temporarily or permanently ending it.
There is no courage is dropping your pants for an affair partner.
Mozza, my guess would be that your psycho-therapist is an adulterer. Any indication that adultery is good is oure evil and you should RUN from that persons office before such thinking gets planted in your own brain further.
I will be praying for you both and suggest you seek good solid Christian counseling. I'm not a fan of either Imago or Nouthetic Christian counseling. I personal prefer more direct coaching but it's better than some psycho-babble psychotherapist telling you things like "your wife is doing the best she can" and "her cheating on you was a healthy behavior breaking free from a dysfunctional relationship because you were pushing her away [thus her cheating is your fault]".
Your spouses have agency for their behavior. They are responsible for it just as you are responsible for yours. Don't let anyone put their sinful choices in your lap. Here's your dead cat back.
The internet is 90% complaining and entitlement and I hate it because I deserve better!