When I stopped trying to be a good DIL, stopped trying to like them, stopped trying to get them to like me, stopped the olive branches, just emotionally disengaged from them, my mental will-being around them improved. And our overall relationship gradually improved.
DH almost always had my back, but he often did not see or understand the issues. From the very beginning, though, he was firm with them that he would not bring our dc to see them without me: we came as a package. End of. Much as I didn't want to see them, dh was right. His parents didn't want me in the picture and were pushing him to choose between us. He made it quite clear to them that we were a unit. But it nearly broke him. The only time I've seen dh cry.
But, as I said, once I stopped caring what they thought, over the years our relationship improved, especially between me and MIL. FIL merely tolerates me. But I don't care.
So 26y and several dc on, can a marriage survive toxic ILs. Yes, I think so. 3 things have helped: me not caring, dh having my back, and 250miles between ILs and us.
(I have always been a good DIL,
though, even when I stopped trying. They haven't a clue.)