You can't sell without her consent because you both own 50% each, but here's what the others didn't explain well: you don't need a partition lawsuit if what you want is your share of the money. You can request a "licitud de división" where basically you tell the judge "I want my half in cash," and then the property gets sold automatically, your sister gets her half and you get yours. It's different from her blocking a regular sale because here it's not an agreement, it's your right. Anyway, before going to court try to negotiate: maybe she'll buy your share, or you two find someone interested in investing in the property with both of you as partners. A lawyer specializing in inheritance law will be able to guide you better on which option is fastest according to your country's laws.