Welcome to the forums! I'm so sorry for what you're going through. There are some similarities to my situation, with some big differences. In my case, the wife and I had been married 13 years, had a couple of young childen, and had been involved in swinging for quite some time before we decided to open.
If you guys had a big investment in a marriage, and children, my perspective on this might be different. But as it stands now, I'd let her go. Sexual attraction is a fickle thing, and I'm sorry she seems to have lost that for you. I'd concentrate on being the best person I can be. I'd get a life by pursuing hobbies, working out, learning new skills, and being the best person I could possibly be. I'd contact her very little, and I'd not intrude in her life at all and just let her do what she pleases. I'd even start pursuing some dates. Who knows - she might begin to see what she is missing and come back. Even if not, you'll be a better person and you'll be a better partner in the future to some lucky lady.