Natasha said it best - she gave you very wise advice.

A few things I noted:

1. This is affecting your mental health

2. You don't typically have issues misunderstanding other colleagues (focus on that last word as you chose)

3. You don't understand each other was how you labelled the problem

4. You think of her as your buddy: your gee

5. You are disagreeing and arguing AT work; who is under whom?

Question: you said, we started working directly under each other -- who is the supervisor between the two of you?

6. Your last line: save my friendship - tells me a lot about your heart

Your friendship is not falling apart - it's that you are not learning to separate friendship from a work- relationship. This is what Natasha nailed in her comment to you.

Work is about accomplishing tasks, efficiently and meeting deadlines and making the company money; there is nothing personal in the business - until we make it personal and think it's personal. Your friendship has muddied the waters of your understanding of your role, and that's why you are so torn.

You probably feel undervalued, or not being appreciated, or that your ideas are being rejected.

Eliminate that from your mindset. What is being asked and required of you : go to work and do just that.

IF you and her - can actually learn to separate business from friendship - you'll have a surviving friendship.

There are MANY friends I have that I could NEVER work with nor LIVE with. I know the boundaries of the relationship, and I have lived much longer to be able to practice patience and tolerance.

Eboh - it's all in your mindset. And then be clear with her: tell her while in the workplace, you too will talk to each other exactly as if you're just colleagues. Show each other the SAME courtesy, respect and SPACE that you do for people who are not your buddies in the workplace.

You said it: you don't have issues with uour co-workers.

She is your co-worker now.

Wishing you peace and calm/reasoning mindset. Get some rest.