Regency.She, orphan with 3 brothers, writes article about men using women, he finds who she is, he has a bad uncle who wants to destroy him.

[Lilli]

She is eldest sister with 3 brother, orphaned, no money. She writes articles on bad behaviour of aristocrats and keeping mistresses. He is a Duke or something and is angry because she is wrong and he tries to help a woman whom the heroine believes to be his mistress.
He tracks her down. He has friends (from other books I have not found), one was a pirate. He tricks the h into marriage somehow. His uncle is a bad man who says that the hero killed his wife, which is untrue and this uncle is the father of the child of the woman this lord tries to help.
In the end, the heroine spreads the rumour that the uncle is crazy but was responsible for the marriage.
I don't remember title or author but it was well written and I read it possibly in the last 2 or 3 years. I moved from the US to Europe and many of my books went to Goodwill but I miss them.
Thank you or trying to help me find it

[Annamariah]

I am 99% certain you are looking for The Dangerous Lord by Sabrina Jeffries.

[Lobstergirl, au gratin]

Lilli, are you still looking for this or did you find it?