Most of the boundaries I have set are around how she interacts with me and about the OM. When we talk if she gets mean or defensive towards me I will just end the conversation and leave until she is willing to talk to me in a civil manner. And with the OM, I don't want to hear about him at all. If she is here and feels the need to text or talk to him then she needs to leave to do it or at a minimum go outside. That I am moving forward to us seeing a mediator to start figuring out the financials, custody of D3, and such unless she breaks it off with OM and starts showing wanting to work on the R. That's pretty much it so far. For the most part she is respecting them except for breaking things off with OM.
