Romance Readers Reading Challenges discussion

I can’t remember this book that I read but I remember some details. Please help me find this book. The hero is trapped by an ex-lover/ex-wife by her getting pregnant on purpose. He is a single father now and falls in love with the heroine. Toward the end of the book, the heroine herself gets pregnant and tells him. He acts out due to his past and tells her that she got pregnant on purpose and leaves her. The heroine sits on the floor of her house and is found by her brother and sister in law with her house on fire. Do you guys know what book this could be?