Girl lied to me about being single, and she has a fiancé. Can this work out?

I’m in love with this older girl who I found out has a fiancé. She’s in love with me too, but she’s been with him since forever, so she can’t let go of him just yet. What’s crazy too, is that I’m the opposite of that guy. He’s like on steroids, and much older like her. Meanwhile I have more of a model type-look and younger. She really loves me, so much so. And I don’t know if I’m being stupid but she confessed to me about having a fiancé. And I agreed to stay her secret lover till she lets him go. What’s crazy is that she gets super jealous of girls with me, but she’s literally cheating.

Girl lied to me about being single, and she has a fiancé. Can this work out?
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