You'll have to remove the inner door panel and the screws that hold the lock assembly in place. This will give you enough slop that you can pull the entire handle out of the door and turn it 90˚ to disengage the lock cylinder's rod from the locking mechanism.

Definitely fiddly, but doable with some patience. Went through the same thing about 6 months ago in my SDL so I feel your pain. Ironically, I found it easier to get the handle out than to put it back in!

__________________
Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]