I have a different prospective on this, or maybe not.
I was taught at a young age never leave one relationship for another.
the only person you should ever end a relastionship for is YOU.
After being with someone for 20+ years, you need time to get to know you again. You need to get an apartment for yourself and figure out what you want in life. Sign a 1 year lease on some little place you can decorate the way you want, not the way you thought you wanted in your marriage.
The world is your oster right now, discover all the things about yourself that you never knew.
It's just one year, you can still see BF as much as you want and hey maybe become really good friends with hubby again.
IMO if you just go from one relationship to another without taking time for you. It wil end badly and everyone will be hurt, mostly you...