Help! Virgo crush on Unavailable Taurus

Hi All! I'm posting this on the Taurus forum as well. I need your help!!

I've got two questions:
1. How do I get over a crush on my unavailable Taurus friend?
2. How do I address my weird "crush" behaviour over the past few months with her?

The situation:

I'm a Virgo--she's a Taurus. We work together in different departments for a small non-profit organization. We've been friends for a couple years--we're both part of a group of coworkers who have lunch together and, on occasion, get together outside of work. Soon after I met her I realized we just get along--I love her personality, her sense of humour (we're always gross/inappropriate together), her earthy sexiness, her intelligence and diplomacy, and of course when she laughs I glow from the inside out. I have a huge crush on her.

The problem is that my friend is married to her partner and I'm in a serious relationship as well. The four of us have hung out as couples. Her wife is lovely and I get along well with her too--in fact, her bday is exactly one week before mine (fellow Virgo). While my partner (another Virgo) and I have a strong relationship, I've never felt feelings for another woman before while in a relationship, which has made me feel extremely guilty and like a pile of sh!t.

I realized I had developed feelings about a year ago and I've been acting funny around her ever since. At first, I got extremely nervous, with sweaty armpits and stuttering. She would catch me staring at her and there would be a nervous tension. I swear she flirts with me, but I tell myself it's probably in my head...and it doesn't matter! I thought I'd got over the stupid crush phase but realize that it's only getting worse. My behaviour is more hot and cold and I find myself acting like a douchebag and not being able to talk about why I'm acting out. As such, I feel I have to address it somehow but am not sure how.

Enter questions 1 and 2.

Help!! 😢