my wife felt we were more like friends and not as a couple. Lacked passion. I was negative and needed to change.
The loss of passion is what happens before the first step of a wandering heart. This is where her interests went outside the relationship.
Went to a shrink. Started to look at some options for low testosterone. Basically I was the a hole of the relationship. Turns out I am not that messed up. If anything I have been looking at a lot of things in the wrong frame of mind. Small issues were just over analyzed...
Good. Very good. You did your part, by working on yourself in the interest of the relationship. Most problems in relationships are 2-body problems, so you must credit yourself for improving your part of whatever was going on.
Small issues were just over analyzed...until today... I find out she has feelings for a woman... who is a lesbien and works at her school! She said she has feeings for her and is not sure what to do.
Your wife is basically coming out of the closet as lesbian/bisexual, and I highly doubt lack of passion drove her to it. She likely had this leaning for a very long time. Despite being able to rationalize why this has happened, it is no less of a negative signal for you.
A, What went wrong and B. What do I do now. We have a 4 year old son who is in the middle.
A. To my point above, I highly doubt that "you went wrong" here. Lack of passion in your marriage/relationship does not normally lead to people "changing sides". She went wrong. And if like I suppose, she really had this leaning toward women for a long time, she should have been honest with you before starting a family.
B. I recommend divorce; there is no changing your partner, and seeking to understand her proclivity for woman achieves little for either you or your son. Consider that for you to stay with her (assuming she was willing, perhaps for sake of the family), she would be lukewarm for you and hot for some woman. Could you live with that? I couldn't.
Focus on getting the upper hand in your divorce (e.g. custody of son + better than 50/50 of net worth).
Do you have evidence that she is interested in (and perhaps dating) a lesbian at her school? If so, this might improve your odds at coming out on top in the divorce.
Realize though that custody is not guaranteed. Your chances of that will vary by jurisdiction. In the states, I believe the biological mother is favored in the courts when it comes to custody battles. That aside, if she's gone lesbian this far into the relationship, you're in a better position than (per se) had you cheated or just wanted to split.
If you go down divorce lane, check your local laws and consult with a few family law attorneys. Good luck!