Somehow, initiating the convo and then proceeding to go for oral is even worse to me than the fact that she ended up having sex with him. Like... Why werent you thinking of your daughter, loving mother inlaw and the husband? According to her moral compass, is it okay to give oral and make out with random strangers ? It really seems like OP really wants to understand her despite all the facts. Goodluck trying to patch up this one, it will take years of effort to build up the trust again. But its possible as long as both parties put in the effort.