One of the hardest times in our marriage was when my husband's brother was dying. It changed my husband and killed him inside. He was a wreck, and even though he figured out how to cope, it's 11 years later and he's still not the same man I married. We only had one newborn at the time.
Recently, we lost my father-in-law after a very rapid decline in health over less than ten months. It was incredibly difficult, and this time we had three children all old enough to know their Nonnu was dying. My husband idolized his father. On the surface he handled things in the end well, but he's devastated and he didn't handle the final ten months well at all.
His mother needed him. His sisters needed him and he needed them. His father desperately needed him. For months on end, he was helping care for his father and the kids didn't see him much. We fought more because of the stress and tension, and I knew that I had to turn my eye away from most of his harshness because it just wasn't him. But his father legitimately needed him, as did his mother and sisters. He had to take on that responsibility.
I just had to remind myself that when the time comes for me to need consideration for my siblings and parents, he'll remember my patience and how I encouraged him to go. Our normal boundaries were lower than usual, but that was all right. I knew it wouldn't last forever.
I also had to remind myself that watching my husband care for his father and mother and sisters the way he was throughout that entire ten months the way he did, the way we all supported each other, broken boundaries and all, was teaching them through example.
I know he recently said some things that hurt your feelings and I hope you got over them. Even though he said them in anger, he had a right to feel that way. He was right to put his father, his parents, as a number one priority right now even if it means you're not comfortable with a certain seeming lack of boundaries right now. When your FIL has passed away, when the funeral has passed, when the initial mourning period and shock of it all has passed, the old boundaries will go back up.