Weird Conversation

My sister-in-law, Grace, and I get along really well.
She is more like a sister to me.
Like a big sister I never had. Until now.
I love spending time with her and we make a good team, I think, when we have to do things together.
As we have found out in the last few years.

To top things off, we sort of look-a-like.
Dark hair. Darker complexion. Dark eyes.  Similar body type.
At one point, her mother, my mother-in-law, mistakenly thought I was Grace from behind.
We have been asked many times if we are "real" sisters.
This weekend was no exception.

Grace and I were setting up some tables for a family baby shower this weekend.
A distant relative who was in town came up to us.
The following happened:

Distant relative: "Are you two sisters?"
I look at Grace and she looks at me.
I say, "Sorta" and smile.
Grace smiles as well.
Roger hated to be reminded that we looked alike and could be sisters.
Distant relative: "What do you mean 'sorta'?"
I was thinking: "Really dude?"
I said: "I was married to her brother."
"Oh, are you divorced?"
Thinking: "Oh my. Really?!?  Because no one my age is widowed, right?"
But said: "No. My husband died."
"Oh, that was you?! In the car accident.  I saw the pictures but never realized..."

Then the situation just got awkward.  I just smiled and zoned out.
Grace, living up to her name, handled the situation.
I just continued to smile and say "Thank you" after he offered his condolences.

I hate getting "caught" like that.
I did not think this weekend or place would ever have those weird conversations.
I guess I am never safe.
I really need to come up with an approach.