The Long Way Home - Cheri LePage

It’s 1890, and after Loren’s first husband is murdered; her neighbor Zack forces her to marry him in order to find the treasure he knew to be on the land. When he can’t find it, he shoots Loren to get her to talk, when she refuses, he throws her into the magical well. 

But when she wakes up, she finds she’s alive. Her first husbands several greats-grandson, rescues her and she finds out the year is 2005, they decide to find the treasure and make a life together.