I sort of think if you wonder for just ONE SECOND if you might get arrested then chances are it is not a good idea.

What on Earth good would it do to involve an elderly woman in all this drama? You assume too much. So what she comes from a different generation? That doesn't exactly mean her values are stellar or that she will "ream" her son out for being with your EX. Her values may not reflect the values of her son and there is nothing a mother can do about the way a grown son behaves. Just like there is nothing your parents can seem to do about the way you behave even if it does go against their values.

You are not exposing an affair to the OM's spouse as the OM does not have a spouse. You are involving an elderly woman that may or may not have any clue what is going on. You have NO CLUE the type of R the OM has with his mom or what she may or may not know. For all you know the OM has already told him mom and filled her in on the night you stormed over there. Maybe she thinks you are the crazy one.

I can't for the life of me understand why you would take such a risk when (A) you are quickly losing any credibility for joint custody (B) you have already made a spectacle that almost resulted in one arrest and (C) your EX has made it perfectly clear she does not want you.

You really sound like you have gone off the deep end. And the person that will suffer the most is your daughter.