Hi Georgina, you have already had a mass of comment and advice, so just one thought from me. it's tricky to find the balance between showing a character as racist and being accused of being a racist writer. its a very sensitive area.
i wonder if the probelm here is the description of Anthony? Cat's reaction would be the same, very likely, if Anthony was white, but still 'enourmous' and still with a large dog. But if he was black, but a bit shorter than her, and carrying a cat basket (no pun intended) then her reaction is over the top and can be seen as racist.
Would a woman alone in a dark park be terrified by any man approaching her? if you tone down the stereotypical description, that might sharpen the focus on her response, then you could give her generic panic thoughts, or race-based assumptions, to suit your purpose with this scene.
i hope this helps