i divorced my wife 6 years ago when my son was 30 months old, long story, not far off what you re experiancing now, if the therapy thing doesnt work out for either of you, get a good lawyer in regards to your child, verbal agreements dont stand up in court in regards to visitation / custody. trust me on this if you dont do it right the first time, there is no second chance and you will be setting yourself up for a whole world of hurt in the years to come, you will have to come to some kind of amicable agreement with your wife regarding your child, so when / if the sh.it hits the fan and you split you still have a solid plan in regards to the child, make a appointment with a lawer to see what options are open to you in regards to this,
good luck and i hope you never have to use any of this advice