Trust yourselves. You can give only what you have; you can't change that. And you know what? Being afraid can be a good thing. If you're afraid of hurting these people, chances are that you won't. If you were afraid of fire, would you let it burn you, or would you be careful around it? I'm sorry if I'm not making much sense lol

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Even if you don't think you're what your friend needs, I know from experience that it can mean SO much just that you're there, that you're really trying, despite everything else you have going on. Just trust yourselves, and try to trust these other people, little by little. Chances are, you'll surprise yourself, in a good way.
Take care, dear heart. We're here for you, as always.