You've brought everything in your life there because there's something you want to learn from it.

So, let's see... Sandy's in my life to help me learn -

+ how to genuinely communicate with someone in a healthy way - without sarcasm, snark, hurtfulness or maliciousness.

+ the importance of understanding that no one's path - absolutely no one's - [even those closest to you] is the least bit under your control. The only way you can influence someone else is by genuinely living your own life to the maximum extent possible, and perhaps influencing them by example. You can't "teach" anyone anything they don't want to learn. Just worry about your own development, and leave their development to them. [Of course realize that part of your development, and their's, may involve interaction and sharing of ideas and perspectives... a mutual understanding and exchange that both need. Nothing occurs in a vacuum.]

Once of learned these... really learned them... I'm sure other things she's in my life to help me figure out will become evident.