As a PP said, there is no objective bar of 'unhappiness' regarding leaving a marriage.
Also, and most importantly for your view of yourself, there is no objective bar of 'sensitivity', either, so if you're sensitive about a thing and he's making you feel like you're at fault for that, who does he think he is? Does he think he gets to make the rules about how sensitive or how x or how y you are allowed to be? Why does he think he gets to make the rules about that? That's your emotions. That's who you are.
So, when you say' 'Oh, maybe it's just me being sensitive...', well, you're right, it absolutely is. But don't view that as a negative thing. Anybody who loves you will be gentle around you with regard to your sensitivities, whether they seem to make any sense or not.
Take the example of a couple, where one is afraid of harmless spiders, and the other is not. There is no objective basis for the fear, right? The spiders cannot do anybody any harm, so, objectively, it's just a bit silly to have this sensitivity. What would a sensitive partner do? Shove spiders right under the nose of their phobic partner? Or try to keep them from ever having to see a spider?
Your partner is shoving the spider of this friend's name down your throat, and trying to make you feel faulty for getting upset about it. Don't allow this to carry on. With this 'spider' or any others that you have.
Choose people who respect your emotions, rather than trying to have emotions that line up with other people's expectations. The only thing wrong with you is that you are in the wrong relationship.
I just wish he would be kinder but I think he has a deep seated resentment of me, which is why he seemingly goes out of his way to knock my confidence
This may be true, but it doesn't matter. Really, sentences like these need to stop at the first clause. 'I just wish he would be kinder to me. But he isn't.' Managing what's going on is his responsibility, not yours, and if you spend time thinking about how and why his mindset is the way it is, you lose time when you could be thinking about why your mindset is the way it is.