So glad to hear you're feeling more positive.
And yeah, on the time split question, think of it this way... I'm sure that your gf and your friend would *much* rather work out a good compromise that will maybe have their relationship moving slower but that will allow you to feel sane, happy and secure, versus continuing in a situation where sooner or later your will's gonna break and you'll either leave her, ask them to pull the plug, or just get very depressed.
Me, 30ish bi female, been doing solo poly for roughly 5 years. Gia, Clay, and Pike, my partners. Davis, ex/friend/"it's complicated." Eric, Gia's husband. Bee, Gia and Eric's toddler.