I'm sorry things didn't work out with Jack. I look at you now and think how very different you are in your attitude to this breakup compared to what you were like this time last year when the reality of your breakup with H was hitting you. I know it is not the same. You did not have a planned future together. There were no hopes and dreams. No expectations. Just the here and now. I guess that's the difference - the expectation of a future together. Jack didn't blow up your life. Throughout your (albeit) brief relationship, you maintained a sense of yourself as a person. I think that would definitely be my takeaway - never lose ourselves in an R because its bl**dy painful finding the road back if it goes t*ts up.
Your life is your life. Full with or without someone. Hard lesson to learn. But worth it, I think.
I'm glad you're posting again. If exH/OW continues to read that is on them. And well, at this point, it's just really sad.
Oh, and I like flirty DV. Have fun out there and be careful.