Boundaries. These are to prevent harm to you and your D and SS. It is about what you will and will not accept.
Smoking a joint outside - fine (why she is doing this but hey?). You don't want kids growing up around that.
Affair and WiFi - again fine.
Respect in her attitude or words towards you is most important. If she is abusive or disrespectful. Just say, "stop, I am not hear to listen to nonsense anymore", then walk away.
The rest is simple, talk to her like you would a work colleague, neighbour etc. Someone you have no emotional ties to. Act as if where you are not detached fully. But work on detaching. The way to avoid this is to fill your time with other things. It will stop your mind future forecasting which is the seedbed of anxiety and stress. The more you do that is healthy for you (exercise, talking particular people etc) the better. You are getting stronger all the time.
I hope this helps.
Surfer.
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