You wrote you need help but don't know where to start. My personal thinking would be to perhaps start by seeing a mental health therapist or a counselor of some sort. I see you list yourself as being in Europe. I don't know what mental health services are available to you where you live or how they are provided. Seeing a psychologist or psychiatrist may be other options. (Where I live, though, all most psychiatrists do is to prescribe & monitor psych med's and I at least would not want to start there.)

I'm not a mental health professional. So I can't suggest what your diagnosis might be. But some of what you wrote sounds to me like what I associate with borderline personality disorder. Here's a link to DocJohn's article, from PC's archives, on the subject of BPD along with an article on living with BPD & a BPD quiz you can take:

Borderline Personality Disorder: Symptoms & Treatments

Living with Borderline Personality Disorder

Borderline Personality Quiz | Psych Central

You may also want to take some of the other quizzes & tests that are on offer here on PC. Here's a link to the listing of quizzes & tests that are available, just in case you haven't already found it:

Psychological Quizzes and Tests

My best wishes to you...