so me and my sister bought a house together to flip back in march and put equal investments in the house. to put a long story short she fought me on everything but refused to to offer any counterpoints and went with my plans. and the house just went on the market a week ago and we both stand to triple our investments. then last night she messaged me letting me know that she just want to give me my starting investment minus a half for a separate thing that is unrelated to the house. I'm trying to talk to her about this but i think i am going to have to take her to court. what sort of lawyers should i be contacting?

TL;DR sister trying to buy me out of a project at starting cost at the end of the project.