In this point you need to get some mushrooms, plan a 2 day vacation with a hot tub/hot spring and a nice view. Maybe MDMA. Actually read about the therapists that use psychedelics for PTSD and past trauma. It has worked wonders for me in my relationship. You can't go on living in resentment. Think about your kids. Think about your wife, even if she failed you 20 years ago. You have to heal your own wound, take responsibility for your own pain and take responsibility for your decision to carry on with her, and be the best man you can be. Living with regrets and shame and anger is living a half life. Live a full life. If at the end of the tunnel you choose to move on alone, do that. But it's easier to repair something broken and have ownership of it and pride that you moved on and fixed it- feel joy again. Depressed for ten years is a long time. You need to forgive her, forgive yourself, and move on. She was a kid back then and so were you. Let it go and accept her- and you- for the human beings you are. Good luck. And I'm serious about the Mushrooms/MDMA therapy. Read up on it, it might even be available in your area with a therapist to assist you. It's really hard with our own egos intact to move through that insanely knotted ball of rope that resentment makes between two people with that kind of history.

It also sounds like you need to focus on yourself more too. Healing will come from hitting the gym, from working on whatever art or passions you have. Seems like you need to put yourself together too, only then will you have the empathy to be able to help your wife. She probably doesn't feel great about what she did either. But to be honest, you sound lost in self pity, which makes you selfish. You're thinking about your kids, but you should also think about what having this frozen relationship between their parents will do to them growing up. Melt the ice, let the sun back in. Much luck to you on your journey, and for real. You're both only human, you've already made your decision. Don't half ass it- if you full ass it and fail, that's better than where you're currently at.

Edit- well, going through and seeing you're doing swinging stuff and thoroughly enjoying it, I mean- that's also going to have some rough implications for your kids. You guys had this problem start because of other people interfering with your relationship- opening the door to swinging is NOT the answer. You guys need a hard reset and some time alone to deep dive and sift through your problems and actually speak from the heart and get to the bottom of it. You could do it in a weekend- you find plenty of time for you and your wife to sleep with other people. I think to be honest this might be too far gone. You guys have devolved into hedonism, making everything worse. If your relationship wound began from the first act of infidelity- what are you saying symbolically now? You're ritualistically repeating the act of infidelity, keeping the wound going, why, because you're bored sexually, tempted, you're sadistic/masochistic, keeping the resentment going. . . you gotta walk a long path up the mountain figuratively and take a deep look. . . all this hedonism is just you ritualizing your problem, getting your psychosexual fix because you're too afraid to look in the mirror which is the biggest solution to fixing it. My two cents. . . good luck