Somebody on a thread here recently talked about 'tipping points'.
Cant remember who it was or which thread (dont think it was this one) but it was about infidelity and lots of posters were ranting and raving about 'deal breakers' and pride and principals and how they wouldnt stand for whatever it was. Then someone pointed out that everyones tipping point is different.
The important thing is that it is actually there. Everyone should have a point at which they say 'ok, thats it for me' and get themselves out before they are destroyed by the situation. I'm just hoping thats applies to you Jack, and you do have an idea of how much you will give and bend and forgive in future should things not be all plain sailing.
Time will tell if your DW is serious about cutting contact with John and treating you with respect and love from now on. Its what we all hope of course. Just have some sort of mental life jacket ready - yes? A tipping point sorted out.