So I'm sitting here at 11:30PM local time trying not to lose my mind as I'm typing this out. Here comes the TL;DR.

TL;DR: Had oneitis on first girlfriend. She broke up with me. Felling new obsession over different girl since 2 days ago. Cannot get my mind off it.

I'm a rather young guy, 18, a few months before graduating from high school. Had my first girlfriend at late 17 (nothing to show for, not a keeper but I don't know better), got my first taste of intimacy that way. I turned full beta on her (cringeworthy stuff: jealousy, worriedness, dumping feelings all over her) so she left.

That is, left me in a puddle of obsession, tears, depression, angst, you name it.

I tried (still try) hanging out with friends often (like once a month as opposed to three times a year) and such, which works in an in-the-moment kind of way. I feel good when doing it but the effects don't last longer than one evening.

Now I met this girl online that is basically a big time sloot, but a smart one. Sucks for me because I'm into brainy girls. From an objective standpoint, there's a 0% chance of dating her, a 0% chance of me liking it even if I did, a 0% chance of it working out and a 0% of me even WANTING to date her. We chat (in a dirty sort of way) like once a week, which I kind of like since fucking at my age and in my environment is kind of hard to do, especially during the school year. I understand that I'm probably giving her validation for it but my very strict father doesn't care for me going out, even with friends, which poses a big big problem.

Now, for the quick summary of my question:

I myself believe I obsess over this girl because I'm lonely, kind of volatile/depressive and not able to fix this due to living in a recently divorced single-parent household. I'm the chiller person of this dad-son relationship. He's compulsive and controlling.

Two questions: How can I stop being lonely and depressive, and how do I stop obsessing over this girl? The obsession, I only felt coming up yesterday when I started thinking about her during the day. Now I thought about her today all day as long as I wasn't busy doing stuff (that is with other people around, I can't focus without thinking of shit relevant to her atm). I contemplated not talking to her anymore just now but I do not want to sever contact, partly because I feel a bit of oneitis, partly because she can advise me on certain matters I will have to face in the near future (education-wise).

I don't want oneitis, I catch myself thinking about her and I tell myself to think of something else but my thoughts come back to her.

I exercise at home (dad's not hot on me going out to the gym) using 9lbs dumbbells and some basic no-equipment exercises. I am pretty skinny-fat but in general good shape after losing a lot of weight last year, now I'm trying to lose my ass fat and become my idealized body type.

Also, I have 2 dates this weekend I'm looking forward to, HB5 and HB6 I'd say without being too nice.

I'd appreciate your advice since I can't logic my way around feelings.