For future reference, both visualstudio.com and github have source code control, and both offer it for free.
edit: as Helb commented, the wsp file is really just a cab file. Change the extention of the wsp to .cab, and then open it with windows explorer. This will give you access to the files that are being deployed, including any js, css, html, etc., files, plus the dll. I'll assume that the decompilers don't know how to read wsp files, so go through this process, and copy the dll to another location, and then use the decompiler from there.