First of all, breathe. There isn't anything wrong with you. You're just going through a tough time right now and really we all have these moments or variations of these moments. It's understandable. But the fact that you don't like the feelings you're having right now is good. That's the first step. In reality it's pretty difficult to just change our mindset over night. It's usually more of a work in progress. Letting out your feelings is good, just
make sure you're sharing these feelings with your T as well. That's another important step.

It isn't your fault that you're bitter right now, but the truth is only you can change that. You're right that negativity often times leads to more negativity. There are still good people in this world, and believe me I understand how it's hard to feel that way sometimes. It might just take that one guy one day to ignore your outter bitterness and look deeper to see the real you. But again, you're the only one who can really change how you're feeling right now because you would still have to be willing to let someone in. Best of luck to you, hope you feel better soon.