Hey Snow- Not sure if you have read my sitch (haven't posted in a week or two) but we have many similarities. My w moved out 8 months ago and I have 3 kids, my oldest stays w/ me and the younger 2 go back and forth to her house and my house.
Anyhow, when they are with her and I haven't seen them all day I will text or call her so i can talk to them to see how their day was and say goodnight, etc..
They are 10 & 6 however. Your s is 2 and I don't recall reading how he responds or reacts to her call. Is it a positive experience for him? Is he confused? I think you setting some sort of boundary or plan is definitely needed. How are you planning on addressing it?
I've done p90x a couple times and really liked it. I'm doing the Insanity program now.