How to deal with a copycat?

There is a girl on Facebook that is being what I call an “art copycat”. I recently did a traditional marker series where I drew a personified version of the zodiac. After I finished, I posted the series on Facebook like I always do to share with my family and friends. This girl liked each of the pictures and commented on them about how awesome they were. Six hours later, she posts a status saying “it’s official! I’m drawing a character for each of the zodiac :)” I just went ”..........” And then she continues on to say “why not? I’ve always like the zodiac ever since I was 12 and it’ll keep me busy”. Please note that my exact reason I posted in my description as to why I did them in the first place was to “keep me busy”. This is not the first time this has happened. Last time it was even more blatant. I gave her a painting as a gift about three years ago. A couple of months later she posted a piece of artwork she did and claimed it as her own yet the picture looked EXTREMELY SIMILAR to mine. Same color scheme and everything. In fact, the only reason it was slightly different was because I can draw better than she can. But that is the only difference (skill). How do I approach this situation? It’s really irritating and she won’t admit that she’s doing it. I don’t want to be an ass but it seriously bothers me