Good luck OP.
I'm sorry; meeting such a suspicious, hostile reception when you were feeling genuinely unsure of what to do must have been a bit of a shock.
Firstly, your co-worker is unreasonable. She either knows what she's doing, or she is as thick as pig-shit.
Secondly, the early reactions to this thread? Don't take it personally, although it must feel dreadfully personal, and don't think it means you're unreasonable to be offended.
The thing is, MN has a long-standing problem with trolling and fishing for anecdotes about gollywogs (and some occasional genuine people seeking advice on how to handle social situations involving the things). So we get threads that are manufactured either as a vehicle for gollywog promotion, or as an opportunity to upset ethnic minority MNers. For example, people claiming that they own one, they have placed it in the front window of their house, and they totally can't understand why their black neighbours find it hostile. Then they and a rag-taggle of other racists spend 500 posts trying to wind up BAME MNers by being creatively dense and calling them over-sensitive.
Sometimes the OP poses as a white person who finds gollywogs objectionable, and then the OP or the OP's mate posts under another name, claiming to be a black or mixed race person who lurves gollywogs, and says that it's outrageous that the white OP has 'dared to take offence on behalf of black people'. Whatever format the OP has chosen, there is always at least one person earnestly explaining that gollywogs are actually a symbol of acceptance, because the source book was positive about black people for its time. 
It seems irrelevant to them that we are in 2018 and should be aspiring to greater levels of equality than what might have been progressive in what was literally Victorian times. Or that the things are more than the sum of their parts and symbolise more than a children's book.
So in light of all this, I'm afraid that when you posted, I thought it was another variation on the same theme, and clearly it wasn't just me. If you've missed these threads, fair enough. Good for you, really, because they are disgusting cesspits, and every time we have one, and I read through the morass of justifications for displaying degrading racist caricatures, I'm ashamed to be an MNer.