Hello Mindi and welcome !
Yea - I suspect as you mentioned that the hormones are playing some influence. To be expected - but not necessarily ACCEPTED.
When you're dealing with insecurities (which we all have some) it's helpful to keep one important fact in mind.
Despite pop culture emphasis on it - life (and relationships) is NOT a competition ! Repeat that 50 times a day
Just try to be the best "you" you can be everyday and know if you sincerely tried - you succeeded. Obviously you have some great qualities that were attractive to your husband and now potential GF.
Be on guard for the hormone driven insecure moods and catch them yourself first and give yourself your OWN kick in the behind. Don't become a burden and have to wait for someone else to bring it up.
It's all "choices" we make. Happiness is a choice.
Take care of yourself.