My mom stood me up for dinner last night! How am I suppose to react (brutally honest answers please)?

My mom and I agreed to meet up for dinner. Last night, I have waited for her for three hours and she NEVER showed up. I though she had trouble with the car or work late and I kept making excuses. My mom did that to me before even before she walked out on us. She wanted to have her own life and chose drugs over us before she left. I have been having thoughts about what everyone warned me about staying woth my deadbeat mother that only thinks about herself. I've been in England for four days now. I can hear my best friend saying, "I told you so." I confronted my mom about it and she said, "Well I just forgot," and she didn't even apologize or felt horrible. My mom always disappoints me but at least she had a good excuse.
I'm going back to bed. It's 5:30am where I live and I'll check on my answers when I wake up.