I don’t know which language you should learn, but I thought I’d share a method: I recently found out that I have access to Rosetta Stone for free through my public library. I was just on the library website and started seeing things I hadn’t seen before, so kept exploring, and then there it was! I don’t know how widespread that is, but it’s definitely a program Rosetta Stone offers, so your public library might have it, too? I also don’t really know how it works (Rosetta Stone’s website says their “Library Solution” offers 50 hours of foundational instruction, so it might just be the first level of their program, but that’s still something, especially to get started!)