[Hominid]

My thoughts:

Wait a year to heal. However, do socialize, flirt, get your "sea legs" back. After 18 years and a divorce, your confidence as well as your sense of self and the persona you exude needs reinforcement. If dating is unavoidable, enjoy it. Maybe even hook up so as to avoid being monogamous too quickly. Don't hide in yourself to rebuild - make yourself be social so those parts of you don't wither while you find your sharp edges again and all the parts of you you compromised or buried to try to save your marriage. Practice being you, and find out who that "you" is again, because she's changed in 18 years. Maybe join some groups that are not singles-focused so as not to be drawn into any drama until you're healed a little more, but still can meet people (even singles) without the pressure of being a "singles group".

No need to be divorced, as long as it's in process.

I suppose it depends on how your marriage has ended, but I personally felt nothing like I was cheating. I deserved the warmth and affection, and so do you. It was a great relief when I finally got involved when the shadow of my ex and what I had been through was less intense.