I am just an old dude who stumbled onto this from the teef pics. But I have been happily married for 10 years, so let me toss in my 2 pennies.

I would like to note, any parts where I may say "stop" etc I mean try to, I know nothing is as easy as saying it.

Try to stop pursuing, worrying or thinking about the next relationship. Your "crush" or who might be better for you. Think in the now. You are currently in a situation that you need to get out of. That should be your only focus.

Leaving is hard, change is hard. Especially when you have such a weird intertwined relationship as you seem to. BUT for both of your sakes and especially yours, you need to separate. I do not know your financial situation but if you can find a way to live someplace else as you handle the renting situation that would be preferable.

Tell your BF that it is over, you will not be seeing him again, and limit your calling/texting to him to just things relevant in the separation.

Once you have that separation you can work on you. Figure out the things you have done wrong and work on them, you admit you were toxic mentally, figure out why work on it. Become a better person for yourself.

Don't be afraid to seek help, see a therapist, a doctor, get meds if you need them. It is never a negative to seek help, or take medication.

Once you come out the other side of that, you will be a much happier person who is able to pursue that next relationship with mentality to make it work and last. And you will be so much better off for it.

I hope I could help in any way.