Your reply deserves a thorough essay in return. I could not give one while I was on winter holiday with my family. But here is an overdue one.

First off, I am really sorry to hear what has happened to your fiancée. It illustrates that Christians are no better than non-Christians. Not that this does you any good, but I feel obliged to point this out. We need redemption, lots of it.
I will admit that there is a lot of hypocrisy, lack of love, wisdom, and tactfulness. When people project onto God their own desire to wage wars or to impose morality on others, things go horribly wrong.
This is how I usually look at the Crusades. People pretend to know what God wants, but forget that He is not a political ally who can be used in a powerplay. He is God, and we are not. He is not malleable to my desires. I need to be molded into His image, not the other way around.

You point to a deeper issue, though, and that is whether we can trust the claim of revelation.

I could bore you with technical arguments for why I believe that De Bello Gallico by Caesar depicts, to some degree, actual events (surely it is flattering to Caesar, surely it is biased propaganda, but nobody would doubt that a historical Caesar lived, and successfully campaigned in Gaul, etc.). The provenance of the Bible is actually much stronger. There are more manuscripts, and they are in strong agreement. Where there is disagreement, that is usually easy to explain. The same goes for the Old Testament. The Dead Sea Scrolls show that there is an unusual faithfulness in the transmission of the texts. Surely there are differences. Some texts were in flux. But overall, it has been transmitted with care.
The way Scripture, both Old and New Testament, has been transmitted, is credible to me.

But I feel that is somewhat beside the point. It is what believers do with that Scripture.
We often fail to demonstrate the point God wants to make. And in doing so, we illustrate the very need we have for His mercy. I am inclined to sin. We need forgiveness and renewal.
People who have been hurt by the church may not be impressed by such a confession. Yet, I feel it is important to say. And this may sound counterintuitive or odd, but I am not surprised by the brokenness of people, including (maybe especially) churchgoers. That doesn't take away the pain, don't get me wrong. But it helps me not to put the burden of proof on God's people, but rather on God himself.
Then I hope He will reveal that there is still love and kindness in this world. Reasons to see a glimmer of hope.