"As a survivor of two abusive relationships, I feel that I should be grateful for the good things he is."
Have you ever had therapy to help you get over your abusive relationships? I really hope this doesn't come out the wrong way, but although your current relationship may not be abusive, you are certainly following old patterns by feeling you should be grateful, or by allowing any sort of attempted control or manipulation (which this is) into your life at all.
I agree that him saying his first marriage broke up due to lack of sex was a red flag - the (pretty clear) sign was there and you did not see it, which is NOT your fault, but again points to signs that you still have some underlying issues which need dealing with relating to your previous relationships and/or your own thought patterns which left you vulnerable to them in the first place.
Just for some perspective. DP and I go through periods of little or no sex, either me because I'm tired or stressed or him because he's tired and/or ill, or because our work/sleep schedules don't match up for a while. He sometimes asks if I'm in the mood for sex, and I'll say no, and he'll say "Okay" and totally accept it with no questions. Even if it has been months. He would never ever pressure me for sex or take it personally if I did not feel like sex, because he understands that sex is something you really have to want to do, for it to be enjoyable, and he would not dream of having sex with me, if I was not 100% enjoying and into it. Conversely, at times we are at it like rabbits
and again, the difference in frequency is never a problem. I have never felt like I "owed" him sex or that he was frustrated with me if we are suddenly not having as much as we used to. We've stopped halfway through before, either because I said "Actually, I'm not getting into this," or because he noticed that I wasn't really getting into it, and wanted to ask if something was wrong. This is as it should be. This is what a healthy sexual relationship looks like. I, too, stayed for months (years? It's hard to tell where the pressure began) in a relationship where I was pressurised to have sex and it ended up feeling like a chore. I thought it was normal, and I had a problem, but it is not. You deserve better. Whether you will get better from him, I don't know, but I think it is doubtful :( because he has already shown you that to him, sex is all about his needs and whether he is getting enough, and it doesn't matter to him if you want to do it or not, or why that might be, he believes that it is his right, as a Man In A Relationship. I'm sorry.