I can see you feel hurt and betrayed. When did this infidelity happen?
If I'm reading right, it looks as though the infidelity happened while she was still drinking, so over a decade ago. If she's sobered up now, and that sort of behavior has stopped, and things are otherwise okay, do you want to maybe take some time and come to terms with how you're feeling before you make a decision to file for divorce? It could be that she thought, "Why hurt him by bringing up a betrayal from that horrible period? I'll leave it in the past."
Or maybe you suspect she's still drinking, or she's been doing other things, and you're generally unhappy and this is the last straw?