Navigating Trust in a Long-Term Relationship: Seeking an Outside Perspective

Question
Hello.  I understand that you can not actually answer a question for me in this matter.  I am just wanting an outside view.

 I have been with my husband 10 years next month.  I have NEVER worried about him cheating.  The only time that is MIGHT have been an issue was in the early years. Only because that is when he was a bit more wild.  But I don't even think then, just saying that is when he went to bars with buddies etc.(6+ years ago)
 A friend of mine and I were talking (due to the fact that her long term b/f just cheated) and she said she would never think my hubby would cheat on me except maybe with my sister!  I was SHOCKED to say the least.  (she was reffering to many years back)
You must understand my sister is a slut.  She flirts with everyone.  
My friend said that is why she said that.  Just because the way my sister acted towards my hubby. (which is just how my sister is)
This upset me naturally that my friend (who does no really know my sister) said this.
So I asked my husband who of course said it was ridiculas.  I don't talk to my sister as she leads a life style I don't agree with.  But of course through out the years she has been around.
Anyway, I would have never thought this on my own.  As far as I know they were only alone one time ever.  But they did go a ways together.  I was still to young to gamble, so they went to a casino with out me.  Which was fine, I did not want to have them not go.   My sister was from out of town and there was not casinos where she lived and my hubby never had anyone to go with so it seemed like the natural thing.
So my outside opionion question is...... Should I just let this go?  Thanks.

Answer
Dear R,

I apologize for not answering your question sooner.  I have been out of town and did not have a computer available to me.

Here in the US (I don't know where you live), we have a radio talk show host by the name of Dr. Laura who answers a lot of questions pertaining to relationships.  When I read your questions, suddenly her voice popped into my head.  And I knew exactly what she would say to you if you had called and asked her the same question.

You call this person a friend?  This lady is no friend.  What kind of person would plant this kind of negative and destructive thought into someones mind?  This lady deserves a good slap and you should distance yourself from her right away.

If you have no reason to doubt your husband then don't let some two-bit "opinion" of a so-called friend make you start now!  I say, forget it, let it go.  And find yourself some better friends to hang around with.

Go give your husband a big smooch and tell him... "That's for being such a good, honorable and faithful husband".  

Thanks for writing.  

R. M. French