For somebody who says they’re confused you seem to have a lot of the pieces of the puzzle together! Let’s see if we can break this down.
First and foremost, if you’re using sex to keep people away then it will be hard to make a connection with someone where sex enhances your intimacy rather than limits it. For this reason you may want to limit your promiscuity.
Secondly, you’re experience in group therapy, which I think is exactly the right therapy for you, sounded extremely helpful. I would find a way to put group therapy back in your life.
Last, but not least, a diagnosis of ADHD means that some of the symptoms you’ve described, along with some of your thinking patterns, may be very treatable. I would go back to the person who diagnosed you and seek treatment.
My guess is that these three things combined should be very helpful.