Historical about brother’s revenge.

I hope I’m remembering this properly, and not conflating two books, but here goes - the heroine is an young heiress, and elopes with a man she believes loves her, to Gretna and marries him. They consummate the marriage, so it can’t be annulled. He then reveals that he only married her for her money, and has a woman that he actually loves, and will be with her and spend the heroine’s money. The next bit is slightly hazy, but he dies - perhaps in a duel. A few years later, our heroine is out in society and shows no interest in any man. The heroine’s dead husband’s brother comes to town (she doesn’t know he is her brother in law) and he woos her. She falls in love and finally trusts a man. He takes her to some ruins, I think, and has sex with her. He then reveals who he is, and that he has made her fall in love with him for revenge, as he blames her for his brother’s death. She is devastated and gets home and becomes ill. He finds out that he was wrong, begs forgiveness and it all end happily.
i read it about 15 years ago and can’t remember the author. Please help.