Throughout my relationship with my ex, there was always an orbiter. This orbiter was her ex. Anyway, the relationship got stressful because there was no more time for us. She was a senior in high school and I was a College freshman. Our lives kept us too busy and stressed. Her ex has all his classes with her and has been following her around like a lost puppy for months. All her friends see him as pathetic already. So since life kept us too busy to see each other, I decided it was best that we broke up. Days after breaking up with her, she got back with her ex. The only reaction I had was "Why?" and she just said "I find comfort in him." After hearing that I wished them the best then froze her out.

A few days later I decide to log onto SPAM so I could study for my finals with some friends. Since I rarely go on SPAM, I didn't remember to block her. A few minutes after logging into SPAM she spams me with apology messages and begs for me back. She claims it's extremely hard to live without me and blah blah blah. I let her spam my SPAM while I was studying then replied a few minutes after saying "You have your ex now." She explained how he can't do anything for her depression and again, begs for me to come back into her life. She wants me back as a friend, not a boyfriend, because apparently she still loves her ex.

So clearly her getting back with her ex is a rebound relationship and not even her friends see any value in this guy. The girl and I have been best friends throughout high school and it sucks to see all that history go to waste. I don't want to stick around while she's with her other boyfriend, that lowers my value. But every night she begs for me to stay in her life as a friend and I never give her a definite answer.

I would say I had one-itis but I've already been gaming other girls and went on several dates, but for the sake of me being best friends with this girl for years makes me hesitant on cutting her from my life.

Should I game her back? Should I just make her a FWB? Or should I just cut her from my life? Any other advice you guys can give me?

I've been in a few similar situations and I believe in distance first. You both need a time out from each other to let those intimate relationship feelings fade, at least for a month or 2 absolutely no contact. It helps you both to move on...

After this time-out you both can start talking again based on friendship only. This worked for me very well with girls I wanted to keep the friendship and with my best female friend (for over 12 years now) I was totally in love before when I told her I needed a time out..
From my experience at least, you won't lose a friendship just by having no contact for a couple of months..

After the freeze out and rebuilding our friendship, would it be wrong for me to use the straw man technique?

Your post says she mentions her depression.

Do her a favor, and yourself. Back away, tell her you are doing it for her own good as well as your own. Tell her perhaps after you follow cmd's advise that you guys can be friends, but that the potential for emotional torture for both of you at this point in your lives just makes this a bad idea for both of you.

There can come a day when you can be friends, but only after the withdrawal of the relationship has completed for you both.