Even if your wife doesn't want you at the moment, you need to stand by her answer. It's called co-parenting. If you were still together would you go behind her back or would you show an united front!
Your kid knows what going on and he tries to play you against your W. I have been separated for 9 months now. My H stands by me when I make a decision and likewise for me. I work with kids from separated family and they play their parents against each other. It's awful as the parents hate each other!
If you want to save your M, stands by your W when it concerns kids unless you have concerns about their safety!