It is not too late if you BOTH want to make it work out. But there are two main things you would both need to do--at least. #1 is to determine that you will BOTH stop cheating with anyone and will never cheat again. This is a more serious project than it may seem on the surface. Because there are physical pleasures and emotional experiences that you would have to give up, and those would be significant loswses that could not help but affect each of you emotionally -- and it would be very hard or even impossible to share the thoughts and feelings involved in working through those losses that you probably could not share with your spouse with causing even more deep hurt than you have caused already.
That "grossed-out" feeling that you have is technically known as DISGUST; because it is an instinctive gut reaction to throw-up or throw-out the physical/sensory union you used to share and believe in with your partnership. That disgust is the fundamental emotional barricade between you and reunifying with your husband, and the source of the conviction that it would feel more comfortable to walk awaqy from the marriage and start over with someone else--perhaps even the lover you have been cultivating for 4 years--than to go through the emotional twists and turns necessary to find your way (which could be different for each of you) back through your barrier and into the warmth of unity that you once had.
It would be easier on you emotionally to give up on this marriage and start over, because you would not have to face and reexperience the painful emotions of betrayal, self-numbing in order to cope with it, and other self-preservative maneuvers.
#2. If you do choose to meet the challenge of experiencing and expressing to each other all of the painful feelings that you suffered and buried in order to go on living together, then you will probably need to be guided by a skillful emotionally focused couples therapist . Because you will each need to recover many of your buried feelings and listen to those of your partner, because only when you can comprehend what you yourself have felt and hidden from yourself and your partner AND comprehend and empathize with what your partner has felt because of you and your actions--only when you can name and express those feelings of anger, hurt, guilt, shame fear and disgust--and when you can begin to accept and express the remorse you would naturally feel when you grasp the effect of your feelings and actions on your partner--only then can you begin to feel the goodness of each of you within the humility and remorse over what you have felt, hidden, denied and avoided. Only when you can both confess and reveal your "bad sides" to each other do you have a chance to rediscover the "good" within the"bad" and find out if you want to continue your relationship because of its history and because you may never be able to know anyone else as deeply as you would then know each other.
But if knowing each other this deeply shows you motivations in yourself or your partner that are so repulsive that you cannot respect him, then you may UNDERSTAND him as well as anyone ever could, but still not want to love someone you cannot respect. Under these circumstances, your last possibility of being able to transform your moral judgments might come from the skillful interventions of an Emotionally Focused Couples Therapist who could help you realize the emotional basis of your partner's and your own actions, so that they become redeemable as equally human to both of you. (But I could not guarantee that such a transformation of your reception and understanding of your own and your partner's emotions through the mediation of an EFCT would come to pass and would naturally lead to a rebirth and regrowth of respect and love between you.)
#3. The going on dates part is a good contribution to rebuilding a positive/rewarding experience of being together. But I think you will have to experience the process of transforming your buried and long-held-in negative attitudes and emotions enough to develop an emotional habit/routine/expectation that such transformations will continue to come about—probably repeatedly with the guidance of the EFCT expert. A more drastic rejuvenating approach (for the positive antidote to the difficult emotional sessions that would be best if managed by an emotionally skilled couples therapist (look up EFCT in your area) could be to embark on an ordeal together—like a huge long difficult work project in a foreign location, or a challenging wilderness adventure in which you would experience the intimacy of surviving a physical ordeal together and by pitching in to meet the challenges of the elements together.
But #2 is the key process that is emotional, without which you would most likely not be able to get through the layers of negative emotions that are preventing you from reviving the positive feelings you once had. Luckily there are therapists trained in how to manage such transformative processes. IF you both want to go through the purifying fire that is required.