Hi! I'll be glad to be of help with this issue.
I can imagine how frustrating and worrisome this situation must be for you. You are clearly a loving and caring wife and this small mistake has spiraled out of control. This is indeed worrisome. And it must be frustrating for you as well because you certainly could not have anticipated that it would become such a big problem.
And this is really an important point about the situation. Somehow, this small mistake became for him something that has altered completely his life and abilities. This would indicate that perhaps his anxiety about himself and his sense of self worth and masculinity were already problematic for him before you mentioned anything about your ex.
The fact that he has become so depressed and anxious about this that he no longer has the confidence to be able to have sex normally as he did in the past is an indication of this. The fact that you've tried so many good ideas (dressing up, taking time with sex, etc.) but they haven't had normal success is problematic as well. Therefore, I think that it's time for him to now seek therapy help.
I would prefer, though, that you seek a psychologist or psychotherapist who is certified as a sex therapist as well. Here is the UK organization's therapist directory:
Okay, I wish you the very best!
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