Original letters contains scans of the letters from 1945 between Jany and Billy. Additionally, on this page, you can find transcripts of each letter to make reading the archives more accessible. Those transcriptions will evidently be in French. However, please note that these are direct transcriptions, the French has not be corrected in any way to match the modern language.
Additionally, if you click the headers of any given month in this section, it will redirect you to the translations of the letters for that given month. For example, if you click the header or title for September 1945, you will be redirected to the translations from September 1945.