First Chapter Back Story - what's too much?

Last weekend, I took a class about back story in a first chapter.  I know, the first answer to how much back story to add is none. Except...

The reader wants to know your character. They want to know your heroine's (We'll call her Deb) track record with men. They want to know she's a twice-widowed woman who in both cases has been a suspect in the guy's untimely death.  Especially if she's walking up the aisle to husband number three.  Her soul mate. The one who got away in college.

The trick is how much information to bring.  Is having the police detective from the suspicious death investigation sitting in the pew as she walks into the church filled with family and friend enough?

Deb's goals right now, first page, is to get through this wedding ceremony without freaking out. Ultimately, she'd like to have a marriage that lasts more than a year and where the man she loves doesn't leave in a hearse. Especially this man.

Christie Craig (award winning romance and young adult writer) says you have to show some back story because our characters, like us, are who we are because of the events and relationships in our past.  And we can't care about Deb as a reader, until we realize she's not the black widow everyone (except husband #3) believes her to be.

And we have to believe in Deb's motivation to marry this guy instead of just shacking up and hopefully keeping him safe. Maybe his job (a pastor, a senator, a principal) requires him to be 'respectable' in the community. And Deb loves him enough to try one more time.

Which we all know, isn't going to work. Which is the promise to the reader.

What do you think? Is romantic relationship status one of those must have's in a first chapter? Or could you have waited until the reception to meet the grizzled police detective who's convinced of Deb's guilt?

Lynn