dnd 5e – How should I play my character and keep the game fun?

So me and my friends are playing a custom quest where our goal is to stop Asmodeus from reaching god hood. So my problem is I am playing a Warlock who is evil and worships Asmodeus, so should I stop my party from defeating him by playing small tricks and misleading like my character would do or should I ignore this because I think stoping them would make the quest a less fun for my party (My DM kind of implied this without saying it outright)?