Of course. I’m glad to read this and offer what I can. I think what you are referring to is something called “rumination.” Rumination is when a person goes over and over and over negative perceptions. It is one of the symptoms of depression. Often the person doing it thinks it will make things better to try to think them through. But since ruminators keep finding the darker side of issues, it in fact feeds the depression and makes it worse. Since ruminating tends to be negative, friends often get frustrated and start to pull away — which only makes the depressed person feel like a failure as a friend as well.
You didn’t mention if you are getting any treatment for your depression. I do hope that you are seeing a psychiatrist for appropriate medication and seeing a therapist to help you manage your thoughts. The combination of medication and talk therapy is thought to be the best way to overcome depression. Cognitive-behavioral therapy (CBT) has been found to be the most effective for your symptoms.
I don’t have any contacts in Greece to direct you to. But your doctor can probably help you find a therapist. I hope you follow through and get the help you need. You deserve to reclaim the ease in your life and your friendships you once had.
I wish you well.