Clingy, Emotional, Urge to Self-harm, Scared

I'm so worried how my crazy emotions might effect my SO and me. I feel like I'm losing my grip! When he's gone at work, I'm crying and crying. When he gets home, I turn super clingy. I fear I'm suffocating him. Last night I must've been too clingy because he pushed me away. Not a mean push I don't think, I feel like it was out of frustration because I was in his space. And I get that; I think he was in his right to do that. But that's hindthought thinking that way. In the actual moment it happened, I just started bawling. I'm just so sensitive these days! And now my SO just left for work, and literally when the door closed I burst into tears again. What the hell is wrong with me? My SO is great and he's been very patient with my outbursts, but everyone is human and I wonder how long he will be able to be patient. Why can't I get control of my emotions? I'm really worried because I self-harmed when I was younger, and I'm feeling that urge now to pick up a blade again. But I don't want to that obviously, but that's where my jumbled emotions seems to be leading me. I don't know what to do!!