D.P.
B.,
Have you ever been to an Alanon meeting? If not, you really should go. Your parents are addicts. Alanon will help you identify and deal with the manipulative behavior of addiction. And they will help you determine what boiundaries need to be set with the addicts in your life.
You cannot apply logic and reason to the actions/life/attitudes of an addict. Your mom needs detox and recovery. BUT she needs to want this for herself. Maybe not having access to your son will make her think long and hard about her choices and needs.
Your mom is sick and while she does deserve your empathy, like any ill person does, you do not deserve the misery that comes from the bad choices of an addict.
I, personally, would not let her watch my child. Ever.
You can do some rules like these for example:
1. She may visit you at any time, as long as she's sober in your home.
2. She may not call you on the phone when she is NOT sober. If she does call drunk, just hang up on her.
You are right that your first priorities should be your marriage and your child.
Alanon will help you. Really.
You can also read the book: Adult children of Alcoholic Parents. Many times kids of alcoholic parents get very caught up in the role of peacemaker, comic relief or pleaser. Identify whether you are doing that.
God bless and best of luck!