<human>: Condense the text into a few key points

Ok so what had happened was...
My girlfriend of 2 years (let's call her Karen) and my best friend of 10 years (we'll call her Danica) never got along from the first time they met.  Karen always told me Danica had some feelings for me and flirted with me.  I knew it was there but I chose to ignore and deny.  

One night, Danica calls my phone blasting the "I don't like your girlfriend" song by Avril Lavigne.  It's late at night but I was up studying and Karen just crawled in bed next to me and heard the song through the speaker because I had to pull the phone away from my ear since it was so loud.

A couple days later, I confronted Danica about this and she stated it was a joke and she apologized.  We ended up not very much talking for a few months afterwards.  

Time went by, I randomly texted Danica to see how she was and what she was up to.  She asked who it was.  Come to find out, she deleted my number and said she decided it would just be easier on me since she knew every time Karen and I brought Danica's name up, it resulted in an argument. I insisted we stay friends no matter what and I'll just deal with Karen's getting upset.

Several months later, still very little talking going on, I moved out of state for a semester of school and Karen stayed back home.  On a road trip out to California (where I was flying to school from) Karen and I found out she is pregnant. Woo!

A week or 2 later, I'm in school and start talking to Danica again, mostly texting.  I bring this up to Karen, she begins to get upset again, ignored me all yesterday, and is now making me choose between being with her or staying friends with Danica.

I love Karen and our bundle on the way, but it's still hard to give up a 10 year friendship.  

Any similar experiences and/or advice?
<bot>: My pregnant girlfriend wants me to stop talking to my best friend because of some feelings that came up from my friend. What to do?