Hi Melody,
As others have said it is a sad thing, but also from a relationship status not surprising. Ignoring the TG issue here look at the divorce issue. OK she ( and you) are very hurt at the moment. The pain is deep, she probably feels betrayed, she may well feel that her husband has had a long term affair with another woman; You.
You feel betrayed, a life that cannot be ignored finally has to be faced and the person you love cannot give you the support you wish.
Your son.
Children deserve caring and loving parents. There is a host of information that they do not need male / female models in parents. They need love and care. There is no evidence that effeminate males produce homosexual sons, there is no evidence that masculine females produce lesbian daughters. There is a host of evidence that same sex couples (of any gender) bring up healthy, happy children with ' norma' sexual orientations. There is, as evidenced on this web site, a truck load of people who had 'normal' male/female parents who loved their children and we are TG. My parents were so vanilla that would not understand this statement

.
So to my mind you need to discuss this. You are a biological parent of your son. He will not be deformed in anyway by your transition. Getting that message through to your wife is the problem. I live in Australia, a quite liberal country, and in a muli- cultural city. In this city, if I was in your situation the law would rule 50/50 in everything.
Not sure if this helps but get legal advice ASAP.
Cindy