You wouldn't be comandeering or hijacking the story. Here's why. 1) The DM put you in this situation, so he should be willing to deal with the consequences. 2) The rest of the party could decide they don't wanna deal with this, forcing the DM to either QuickTime the entire quest or accept that you're gonna have to roll up a new character.
But I'm also curious. With most roleplaying games, players accept risk that their characters will die or at the very least experience events that will cause them to change in some way. Characters should not be static, but change and grow based on their experiences. The characters do not always have control over what happens to their characters, but they can control how they react. And your DM has already indicated that this may be temporary and there are ways to reverse your current condition. While this situation may not necessarily fit with how you envisioned your character now, it is a small portion of your full character arc. It is a conflict, a problem, a quest, and at the other end your character will likely come out stronger than he was before.
Additionally, I wonder what it means for you to be a revenant and how it changes the way you play your character. From my understanding, a revenant is an undead creature that has risen and driven to seek vengeance against those that wronged them. But they are also intelligent and maintain the memories you had in life. There's no reason this would have a major impact on how you play your character, and could even allow you to explore some neat things about your condition.
For example, if your character was light hearted and jovial in life, there's no reason he couldn't continue to be jovial and light hearted. This might be because being undead doesn't fundamentally change his personality. Or, perhaps he feels numb and dead inside, but he's going through the motions and reacting as he would in life because it's what he knows and what's expected of him (see the way people act when they lose their souls in Supernatural for examples). Either way he's acting the same, but the stuff happening underneath or the reasoning may change, and people don't necessarily need to know that or even be aware of the difference.
Another thing could be that he is mentally and emotionally still the same, but physically has no feeling. He could be clumsy, cut himself while eating and not notice he's missing a chunk of a finger, or whatever but still basically who he was in life.
Or he may be normal as he was in life, but at the mention of his killer or in the presence of anything that reminds him of his killer, suddenly is overcome with a sudden and explosive rage until someone or something can soothe him.
I understand how this may be unexpected and not what you envisioned for your character. But if you keep yourself open to the possibilities, this may become an awesome opportunity to really explore who your character is and a challenge that will ultimately be rewarding by the end.