Welcome to SI Sentric,
I would suggest that you start by looking at our "healing library" (link is near the top left of this page), and also check out a book called How to Help Your Spouse Heal From Your Affair", which can be found online, either for purchase or for free as a PDF if you search for it. These are the best starting points for most people, and will give you "The basics" of how best to start off.
This forum is comprised of WS's from all walks of life, and at all places in recovery. You can find the support you need here, and the people here have walked in your shoes, and know the landscape. The downside of that is, it means we also know all the excuses. And if you try to bullshit a bullshitter, you'll get called out on it. Not to be mean, but in order to help you move past it so you can actually heal and grow.
Your story is a little complex. If I understand you correctly, it sounds as if both of you had an affair (although I'm unclear if you've proven that with your husband, or just suspect it?) That situation, where both spouses have been unfaithful, is called a "Madhatter" situation. Recovery in a MH situation is complex, but it can happen.
The first thing that really needs to be addressed however is ownership. Ownership of what you have done. A lot of what you wrote seems "excusy". You seem to minimize your part (" I didn't deliberately set out to cheat", "I suffered from vitamin deficiencies", "my husband didn’t try all that much" and so on). I'm not saying these things aren't true, I'm saying that none of them are a reason, or an excuse, justification or cause of infidelity. Short of having a gun being put to your head and forced to cheat, then you made a decision, and took action on it, deliberately. It was a choice.
You didn't mean to have an affair, but you did
Vitimin deficiencies don't cause people to cheat
Your husband not trying, or having his own affair, is a good reason to divorce, but not to cheat
Cheating is always about ourselves, not someone else. People who love themselves, who have self-respect, integrity, healthy boundaries, empathy and so on, do not have affairs, not even because of the damage it might do to another, but moreover, because they will never let themselves sink so low, disrespect themselves so much, and be someone they cannot respect. We all had choices. We could have talked to our spouses about how we felt. We could have suggested an open marriage. We could have asked for a divorce. We could have asked for a marriage counselor. However, instead, we chose to do the wrong thing. And each of us needs to "own that". Your husband may have cheated and that's another matter, but for now, we need to address you. Until you regain your self-respect and integrity, you cannot begin to heal. This is a journey of self-discovery. Your husband's recovery is his own as well.
For now, please go check out those resources I mentioned, as they will help you to understand where to begin. Keep coming back, as you will find great people here with lots of advice and support. Just remain open-minded and calm, and honest.
Oh, one last thing. I'm very concerned about the "multiple fake emails to forums for fun" thing. I'll be honest, I don't really believe that it was not related to infidelity. Fake logins are WS 101. And sadly, even if it is 100% true that it is not related to infidelity, then it means you might like to screw with people by using fake accounts, and well, this being a forum, that doesn't bode well either. Now I'm not sure if you are a person in pain who needs help, or a troll who is bored and here to fuck with people who are already in pain. Do you see how our actions come back to haunt us? How being inauthentic makes us untrustworthy? We lie to ourselves before we lie to others. It's time to get authentic.