I have experienced unrequited love but I knew the person for more than a week or two. In one case, it took years for the feelings to stop but time and distance will help the feelings fade.

That you have experienced this with someone you met online "over a week ago" makes me feel like your imagination is running wild. Also, I have noticed that when I have shared very intimate details it can create attachment. I assume if they are not sharing in the same way or if you are not responding in kind then the feeling is only coming from one side. It is a one-side or lopsided thing. An example would be that I went to therapy and felt just regular attachment to my psychologist but when I shared some of my traumatic experiences with her I began to feel more attached because of the way she responded. IMO this is why we have to be careful what we share with others--especially online.

Plus, given how you just met her and haven't met her in person--it was legitimate to have doubts but IMO, it was way to early to express this concern. Perhaps, in the future, you should use those feelings to back off/improve your boundaries rather than revealing your feelings. Just let it play out. Our doubts are there to protect us and people do lie about things. (Not saying she did but also, some people get extremely mad if you say they have lied and if they lose their temper this can also be a red flag IMO. However, since you do not know her in person--it can be harder to judge these things. ) Hopefully, since you only knew her for a couple of weeks, these feelings will fade.

Also, if you are having any sort of fantasies about the situation--try to focus on something else--I find reading, Youtube videos and prayers can be helpful. Have you ever heard of phrases like: We are what we believe we are. (C.S. Lewis) and What we think we become. (Buddha)?? You are young so, IMO, it is a good time to focus on what you want to become in the area of body (fitness), mind (studies) and spirit (becoming a good person) and also focus on what you want to achieve in the next 5 years. IMO, you are at an age where it is good to focus on goals rather that relationships because I have noticed that when I was your age, when I was immersed in school and work--friendships would naturally arise because I was working with people involved in the same pursuits. I know this is harder if you are stuck at home. Are you going to school or do you have a job? I know this pandemic thing is sabotaging the way people your age normally build relationships. Or perhaps it is just a whole new world but, IMO, it IS harder to read people when we don't see their body language. For me, it is already hard enough to make judgements about how other people are feeling who I deal with in person....