I know it seems awful and feels threatening but I try to focus only on what I can control. In most cases, I have found, the only thing within my power to control are my own thoughts, perceptions and attitude. Unfortunately, most people are not on the same page as me, and often do not place my feelings about something at the top of their priority lists.
If the best he can do as a parent in this situation, as you describe, is provide a proxy parent to act on his behalf, then that may actually be the BEST he is ever going to be able to do. Can you accept that? Is there any thing you can do to change that?
My guess is, SHE is actually a lot like US, given that she is living with an alcoholic man. The fact that she is even interested in attending your child's guidance counselor appointment, IMO, speaks volumes. I have participated in these kinds of things as the GF in many of my past relationships with men with young children. I have always tried to work WITH the mothers of those children, in order to ensure that EVERYONE is on the same page and acts in the best interest of the child. My participation was NEVER meant to threaten, judge or say anything about those mothers.