Back To, Well, Only The Early 2000's!!

Ahhh, time for a tad bit of high school drama, six years after I have graduated! But I guess females' never really outgrow the catty-ness that blossoms during those adolescent years.
I met my best friend when we were 7. My old best friend moved away in grade 2, and Dee came in as the new kid and ended up in my old best friends desk, right beside me. As logic would have it at that age, she became my new best friend.
We have been to hell and back in the 17 years since then. We have suffered through losses together. She and I had only been pals for a few months when my father passed away but it was like we had known each other since birth. I was the first one she called when she found out her mother wasn't going to win the battle with cancer last year. We went to different high schools, hung with different crowds, were different people. She was the boy crazy social butterfly, I was the bookworm who was loyal to my small group of buddies.  She has married a man who hates me.  She had two kids before I had my one, and a third shortly after Marlow was born.  She hates animals and I love them all.  I have owned every pet imaginable almost, she finally let her 6 year old convince her to get a fish.  At one point she moved 8 hours away.  We are soooo opposite, yet through all the years, we have never lost contact. 
She dated this boy in highschool, her first love I guess you could say, and got close to his twin sister.  They have remained touch and go friends even after her first love ended sourly.
We had joined a bootcamp in the summer, and decided to continue into the fall.  Dee invited Nerissa, this girl, to join us.  I was fine with that, I'm always up for meeting new people and if she's Dee's pal it meant she was fine.  Plus, I had met Nerissa socially a few times and we had gotten along alright.
But now she is driving me crazy.  It's like she's trying to compete with me for Dee's attention.  She is always pointing out that she spends all day with Dee and that she knows everything about Dee's son(who is allergic to EVERYTHING and has constant problems).  She will make plans with Dee in front of me, loudly.  Like she want's me to know that she is going out with her.  I don't drive so she is able to do more with Dee then I am.  I don't care that Dee has other pals, but Nerissa goes above and beyond.
A real kicker happened a few weeks ago.  Dee didn't have a yoga mat for the workout class.  She just used a towel.  So I was talking to Nerissa and I mentioned in passing that I was going to buy Dee a yoga mat for Christmas.  A cool one that I had seen at Walmart.  Well, the next class Nerissa comes trouncing in with a yoga mat that she proudly presents to Dee, in front of me, and exclaims 'oh, I was just at Walmart and it made me think of you!'  Dee gushed about it, saying it was so her and Nerissa must know her so well.  I just ground my teeth and told Dee it was nice.
But Nerissa is always doing things like this!  We are 24(Dee and I), I think Nerissa is 26.  Grow up!  Dee can have more then one friend, hell, she can have more then one best friend, but stop trying to push me out, it aint gonna happen!
On another note, anyone know what I should get her for Christmas now? lol