What does your therapist say? (You're still in counseling?)

It sounds like you're ready enough. You've done counseling, you're being honest about your situation, you've discussed the risks of rebound and divorce chaos.

I would suggest you sick with the counseling, at least on a maintenance schedule (1/month?), as a sanity check until a few months after your divorce is final. Also , be compulsively honest with your BF about how what you're going thru, but also sensitive to the fact he won't/can't be impartial.

My story is similar in some respects - ex and I in our 40's, one kid, dead bedroom for years, wife had affair, she decided to stay with her affair partner and moved out, I started seeing someone a couple months later, divorce finalized 9 months later.

GF and I are still together and it's fantastic.

Honesty, therapy, and a partner who is understanding and has experience with divorce were all vital in making it work.

I started dating very early in the divorce process. Looking back it's a little terrifying to realize how foolish I was being. But I crushed hard on this person; I'm sure the emotional roller coaster of the divorce contributed to that, btw. But we were both aware of what I was going thru, and talked at length about what it meant. I went to therapy as much to reassure her as I did for my own peace of mind.

Your infidelity is a potential risk. That you cheated once begs the question, "will you cheat again?" I know the circumstances seem to warrant it, but still... As someone who was cheated on I know how disruptive an affair is. The effects ripple out thru all your relationships and have surprising consequences. That this is still a secret from your husband and family means it's not completely dealt with. Hopefully you've talked thru this with your counselor and partner at least.