Griefing from rejection and now I feel like my friendship is ruined. Does anyone relate to this?

I met my best friend on Discord about five years ago, and I fell in love with her. We've been texting each other for the entirety of those five years. We are very close, and there is nothing that we wouldn't tell each other about.

Despite my sexuality, I am a straightforward person, and I don't like beating around the bush. So, I confessed to her about my feelings the moment I realized them. She rejected me about three months ago, with a reason that I also think is fair: because of her depression, anxiety, and ADHD, she needs to work on herself at the moment, and she might not have any romantic feelings toward me. Honestly, I was surprised by the rejection at first. I thought she did like me too because of how close we are, and it was only afterward that I realized that sometimes closeness doesn't always translate to romance.

This is not the first time I've been rejected by someone. But I feel like her rejection affected me more than I anticipated because normally, I would already be in the process of moving on after a rejection. This time, however, my thoughts just refuse to move on and accept it. I thought maybe I was just in love with an idea of her since I had never really met her in person, but then I met up with her in real life and spent several days with her, and that didn't change anything about how I felt about her. It's a very odd situation because she's not the "type" that I find attractive just based on appearance. But regardless, I really do love the way she is, and I would dare to say that I've had thoughts about spending the rest of my life being there for her.

Now, I'm constantly trying to find ways to move on. My therapist told me to try to find something else to focus on, like college, friends, and hobbies. It did help me take my mind off of it for a moment, but whenever I have time alone, those thoughts eventually come back and hurt again anyway. The hurt and grief have gotten to the point where I can't talk or interact with her properly anymore because I keep thinking about the rejection. It makes my stomach turn, and I feel like I might throw up. It's not because I'm disgusted by her; it's probably more directed toward myself.

Now I don't feel like talking to her as much. I can't even make the normal girl-bestie flirting jokes anymore, and it just becomes awkward every time she does it because she's still used to us doing that all the time.

Just recently, she mentioned that after the days we spent time together, she started to think that she might have a crush on me. I am so conflicted by this new information, and I cannot take it at face value because it's not a certain answer. I'm afraid that this might not actually be true.

I feel like an asshole for feeling this way and putting these things on her because she knows I still haven't moved on yet. Am I a terrible person for acting like this? How can I move on from this? What can I do to maintain our friendship?