11bravopapa,
I'm in almost your exact same situation. My addict wife and I have been married for five years and have a 19 month old son. She went into rehab the day before he turned 17 months and is just now starting to transition home while still attending day treatments and meetings. She hid her addition from me for months until I started opening my eyes. She lied to me with every breath and fought treatment until she was forced to go or she would lose her professional license. She ignored our son as well and was always tired, sleepy, etc. She completely missed my 40th birthday.
It is extremely tough, but accepting that I didn't cause her addiction, can't control her addiction and can't cure her addiction was a godsend. Only you can decide what you is best for you and your child. I decided to give my wife a shot because we had four great years of marriage before her addiction and I hope that maybe we will get that back. She has made huge strides but she is not back to the person she was. While I have no fear of her using, she still lies to me about completely inconsequential stuff and uses those addict defenses from time to time.
The only thing I can say is to make sure you give al-anon a real shot and remember that there are many of US out there, just as there are many of THEM. In the end, YOU will know the right answer. Good luck.