I can also somewhat relate to your issue with the exception of the suicidal thoughts or other people . My parents are alive but they really weren't around when I was growing up and so I looked for love and affection through my intimate relationships. I also felt jealous and that they were my everything and if they didn't want to spend time with me as they first did or they began to act different then I would be really hurt .
I am learning that to learn to stay away every time I want to get attached or I say to myself " nope I wont hang around if I am going to be needy or feel lonely or feel sad" Why not ? because I will learn to comfort myself and not leave the responsibilities on others. I have found this to be hard but also so super helpful- I even see myself so much stronger than I have ever been before.
Other people either it be a relationship with a friend or intimate should be around in the good and bad but not responsible for your emotions or happiness and even insecurities . sometimes, changing ones thoughts even if its not true its a start . Like, no I am not infatuated no I don't need that person- even if you feel it eventually you telling yourself you don't will actually work and you will begin too feel confident and not needy .
I hope this helps a little