And am I over reacting...
My honest opinion? More like over-exposed, over-involved in his business to the point of feeling terrible.
Elemental, this is your relationship. Right now, this is the state of your relationship. If it never ever changes, is this enough for you? Do you want to live like this for the rest of your life?
How he chooses to spend his son's and internet woman's birthday is entirely his right. It's his life.
How you choose to spend and define a day of your life is entirely up to you. And it sounds like the way you chose to spend February 15 was detrimental to your wellbeing.
When we choose to take care of ourselves, we're doing it for us, to make our lives better. Not to somehow get another person to come around and treat us better. The focus of taking care of ourselves is not on them, the focus is on us. If the natural course of life then brings someone around to want to be a part of our newfound way of living, great, and we have the option to invite them into our wonderful world or not.
Our world, I want to emphasize that. The world that we create for ourselves.
Boundaries are essential at this juncture. What are your boundaries? What are your values?
A boundary might be, 'I will not engage with a person that is obviously drunk'.
A value might be, 'The wellbeing of children is super important to me; I value their happiness and that they are raised with guidance, structure, love and devotion. Therefore, I will not date a man that chooses to spend his son's birthday, drunk'.
None of this is about getting another person to change, or to heap blame, shame and guilt upon them. It's about getting in touch with how we want to live our lives.
The people we choose to get involved with speaks directly to who we are and our own beliefs, self worth etc... .
There's some payoff for you within this relationship. Do you know what it is?