:(
How gutting!
I can't recommend a cleaner, ours are so different to what you have.
But try a spot remover first, we have spray on stuff that's supposed to lift things like ink. Just do the stain, and rinse that section in the sink.
If that doesn't work, maybe think about soaking the whole thing, being very careful to time it and not over soak.
If it's ink, you may need to try several times to get rid of it.