Guy was so annoying I just murdered him and lost xp, how bad is the loss?

I’m level 7 and I was doing that helm and cloak of balduran quest.

I wanted the xp for the quest but I had to kill him quickly because he disappears.

Basically he summons a bunch of guys in a snall room and the ai othfinding just kept taking moronic paths. I kept trying to complete this battle, I did once, but minsc died so I reloaded. I got so annoyed I just killer the guy and left the quest unfinished.

Is the xp loss for this bad? Can I still hit level 8-9?