Dylan,
Where to turn? Well, turn to your religion, your morals, your background, and turn toward Dewt. Why the last suggestion? If you don't turn toward him you will never see him, and thus you will never know what to do. I don't think you two have been turned toward each other and really looked into each others eyes and hearts for many many years. I think it is time you did that.
You see you have both done enough damage to justify ending this mess, and yet...something is still there isn't it? At this point the bookkeeping of he did this, she did that, etc, is meaningless. You both have hurt each other. There is something still there, but neither of you fully know what it is, and the reason for that is that you have stopped facing each other and being honest.
So Dylan, my suggestion is that you quit running from this. My suggestion is that whatever decision you make will NOT satisfy you until you two turn toward one another and recognize the damage each of you are capable of. Then you will know if each of you is capable of as much love as you are damage.
I don't know if it will work, but neither of you guys seems to want to file for divorce, so I can only conclude that you both deep down have a lot of love for each other. I also think you each expect things from the other, that the other cannot deliver. That needs to be acknowledged and discussed.
So I will repeat my answer turn to your religion, your morals, your beliefs, and turn toward your spouse. That is where I would tell you to turn.
God Bless,
JL