Blue
Ravenous Bugblatter Beast of Traal
1. Do you think I did anything wrong and how am I supposed to play this? I can't like forget that she is an evil lich.
I see no real way of separating character and player knowledge. The best way to avoid inappropriate overlap between the two is for the DM to mix things up.
Let me ask you this. As a DM, I introduce a character that has a name matching someone from a novel or other FR resource. You make assumptions about that character. It turns out it is another character of the same name, just like there are plenty of John Smiths in the world. (Maybe a coincidence, I heard the name somewhere and it stuck in my subconcious, maybe intentionally.)
You end up with a character that did something for no reason they can explain using in-world knowledge, and that action turns out to be completely unjustified. When you are interrogated by the church of Lathander under a Zone of Truth about why you unprovokely murdered their paladin Valindra Shadowmantle, what do you answer?
I don't understand how your character can't forget it's a lich - they never knew it and it may not be true. The player "knows" it's a lich ... except it may not be. Even if it's the same character, it may be at a different point along their arc. Don't assume the DM has perfect information either (an issue I have with FR - so much lore, it's easy for a DM and their players to be out-of-step).