Pensa. Get some help on this issue from you MC. The MC is a neutral party that should be able to assess the situation and help the two of you decide whether or not TKD is a problem or not, and you don't have to be the bad guy.
She may legitimately think that she can handle it and it's not a threat to the M, but she is not objective and she does not get to decide when you can trust her again.
IMHO, TKD is BS. She can find another way to do it or another marital art style. There is nothing special about TKD. I have trained in that style and many others. Placing a particular studio or style in the way of reconciliation devalues the marriage or fails to acknowledge the damage that has been done.
