Reading between the many lines, I think this must be what happened:
Venice took a selfie showing Lily in the background, intending to post it to a private Facebook group afterwards - presumably to illustrate that Lily was there. In this private Facebook group, someone else had made and posted the nasty meme calling Lily a dicksplash. Venice had replied to the meme posting, saying she thought that it was better to use formal Labour Party mechanisms to complain about Lily (Venice's suggestion was that the nasty meme could prompt Lily to up the ante by making some kind of "fake" suicide attempt).
Of course, someone inimical had infiltrated the Facebook group and made both the selfie and the meme public. I don't know why anybody trusts anything to private Facebook groups regarding trans issues. They always get infiltrated and the posts are never private.
In my view, the meme (and also the selfie, but less so) are over the line. It does the gender critical side no favours to be like this, even when we don't think anyone can see. It's just crude and low. And it certainly won't persuade the uncommitted.