I don't believe my happiness is the only important thing, and I believe marriage is sacred, and divorce should be the very last option.
You may believe marriage is sacred. What evidence is there that your AH believes marriage is sacred?
We often see this sort of ambivalence regarding divorce from women who comes to FFSA with drug addicted husbands, and that ambivalence is often rooted in religious beliefs. But while I know and understand that couples take their vows in front of God, it's important to point out in situations such as yours that your AH reneged on the tacit vow you each understood: neither of you would engage in any behavior that would undercut the vitality or viability of the marriage.
You've been with us since October 2013, yet you've only made 37 posts. Perhaps you can take full advantage of what we have to offer here. We have plenty of women who've been where you are and have lived to tell the tale. Reach out to them. Absorb their stories and how they got through it.
And remember one thing: there is never a guarantee that we'll be happy in this life, but at least we should take steps such that the possibility of happiness exists...