I need help please

I’ve had anxiety for the past five years. Right now, I’m going through a painful situation in my marriage. We’re both women in this relationship—we’ve been married for almost 15 years and met when we were 16 and 17. I’m bisexual; my wife is a lesbian.

Yesterday, out of nowhere—while everything seemed fine—she told me she loves me 'in a different way' and isn’t in love with me anymore. She said she needs to 'find someone to fall in love with' and can no longer offer me fidelity. She added that if I’m okay with this, ‘good for both of us,’ but if not, we could divorce.

We’ve been together for 15 years. We have 4-year-old children. My heart is shattered. I don’t know what to do.