Reeses Bride, by Kat Martin

It's been a while since I finished this book. I didn't find it so special, mainly average romance with a lot of cliches.
Eight years ago Elizabeth ditched Reese for an earl, and he has hated her since. Now, Reese has come home wounded from the Crimean war, and Elizabeth is a widow with a small child who fears for her safety and her son's.
What's a wealthy widow to do when she thinks her evil in-laws are poisoning her? You're right: run to her ex fiancee (Reese) and ask for his protection. Even though Reese hates her and wouldn't trust her again in a million years, he accepts... and marries her. Of course, it only leads to passion nights, because now the evil in-laws would rather kill the son and inherit the title & money.
This book has a lot of classical cliches: the abusive ex husband (even though he was a pretty decent fellow when he was courting her, he became an abusive and alcoholic man who is terrible in bed and has weird tastes as soon as he marries her), and the secret child.