Hi NW: Glad to hear that you're doing so well - it sounds like you kept your perspective and stayed focused through a tough conversation - I also think it's good that you let her know that you knew about the OM - and just got that out in the open...some of what she throws your way may be motivated by her sense of guilt - but that is hers to deal with - not yours.
For the sake of your son, I hope her IC goes well and she sticks with it. Are you talking with anyone? It might be a good time for you to consider going to a T yourself...
You're doing great - you've really gotten stronger very quickly.