My housemate excluded us from her birthday and is now asking us to pay for her DJ?

My housemate (we are a house of 7) excluded myself and my other friend from her birthday celebrations. She had a big party but didn't ask us to set up but asked the other five girls, then took the five of them out for lunch and dinner the next day to celebrate her birthday without us. She basically excluded us on purpose. Now she has texted me, asking me and my friend who she excluded to split the cost of her DJ for the big party even though we had nothing to do with it "because it's our house as well." Am I right in thinking she's being really unfair asking us to pay?
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She said "can you pay asap pls" lol. I texted her back saying "I don't think it's fair of you to ask us to pay considering we weren't involved in the celebrations." and she replied "I don't know why you're making such a big issue of this, but if you don't want to pay then fine." LOL
My housemate excluded us from her birthday and is now asking us to pay for her DJ?
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