If you haven't put it in a dryer try an artist brush clearner. There is a package you can purchase in craft store like Michaels or Art Supply (or an artist friend) that has:
1. Kiss off to remove just about everything.
2.The Masters Brush Clearner
3. bar of Masters hand soap. This runs about $7.00 or so.
An acrylic artist pink brush cleaner that is liquid is also good.
I have successfully removed dark brown dried acrylic car model paint for a pale beige carpet. My grandson and friend used cardboard and newspaper to protect but it just somehow got on the carpet. I was visiting and ran for the emergency kit yelling I can get it out -- and I did.
It will take a little slow work but it is worth a little more time to save your wonderful work of art.