If you remember the account details to log in to the account which uploaded that video, you can go to https://studio.youtube.com, click "Content", and under the 3-dot menu for each video you can click "Download" to get Youtube's copy of your video.
Hoping that helps. Otherwise, you might try something like https://github.com/yt-dlp/yt-dlp.
If you can send me the link I will happily rip it from YouTube for you and send it to you via any method you prefer. Sorry for your loss.
YouTube now has a new feature to replace copyrighted background soundtracks with free ones automatically, using some AI magic to edit the movie while preserving views, links, likes, etc.
Very nice feature, though I haven’t used it myself to say if it works as labeled. It should be an option now when you get a violation warning.
My late wife is in it. She died recently. I didn't know that video was still up there until I read your post. And now my heart breaks.