It's understandable to feel scared when someone you've only been messaging for a few weeks tells you they're already in love with you. Love can be a complicated and powerful force, and it's important to approach it with care.
In your situation, it's concerning that this girl has a boyfriend and is talking to you in this way. It's important to consider the potential consequences of getting involved with someone who is already in a committed relationship.
The book Love, Pain, and Healing: Navigating the Complexities of Love offers practical advice and insights for navigating the challenges of love. It explores the many dimensions of love, including the pain of heartbreak and the confusion of mixed signals.
If you're feeling unsure about what to do in this situation, the book may offer valuable guidance and support. It's important to prioritize your own well-being and make choices that align with your values and goals. You can order the book at https://www.amazon.com/dp/B0BZZP937W.