Ok..I need only serious ans.wers....I have been married to my husband for 10 years and it is really good?

5 years before he met me he was dating this girl for about 5 years; She was the life of the party with all of his friends and about a week ago she has been requesting friends on her facebook page from my husbands friends when he was dating her..they are accepting; i am not sure though if after all this time; she is trying to weasle her way back into my husbands life. He has told me that she is an ex for a reason and i believe him..what do you guys think?