i know i'm old - a child of the 60s.
but we had a saying,
let it go.
if it flies away it was never yours
if it returns, cherish it.
there is also one of my most favorite sayings,
in the bible it says "my cup overflowith"
your cup must overflow to share your love with someone
your actions with your g/f sounds like my ex-wife. she was jealous and possessive. when i was working she would call constantly to make sure i was at work. she stifeled me to the point that i couldn't breath. actually, she had nothing to worry about from me. finally i couldn't take any more stifeling and divorced her.
don't make the mistake that my ex did. back off. get help with your secuity issues. get a diagnosis that fits the symptoms and take the meds.
i know that you are having a hard time. we are with you.
i wish you all the love this world can bring.