Why do i do this to myself?

Today was the first time I had felt so done and tired with life in a long time. I felt so much sadness I couldn't do anything but just cry. Depression is normal for me but I had been pretty good about the suicidal stuff. I felt okay for a bit, or as much as one person could feel. the problem is I keep pushing people away. Due to the fact I know they are hurting me, but then I get lonely and after I push them away I want them so badly to reach out to me and give me that attention. The thing is it never happens and it's selfish for me to expect it when I act so unjust in the first place. I don't know how to deal with these emotions. One person comes along and I'm their shiny new priority, till I get bored or someone else comes along who is newer and shinier than me. then that once-held priority I was to them slowly goes away till I'm just the friend they hang out with when they are bored or they can't hang out with that new person. A person of convenience. That is what I always am. They reach out every so often. tell me they miss me, we start to hang out but the entire time there texting them and it doesn't feel like they are interested or care anymore. Then immediately when they are available I'm tossed to the sideline. All attention is on them. I'm nothing but just a faded memory to them and I just sit there and watch this person who just said they missed me only use me because I'm always there. So I distance myself. hoping they would notice and sometimes they do but then they don't care anyway. Or say nothing has changed. They hit me with I miss you or I love you every once in a while. All I feel is pain when I'm with them now, but I don't want to lose them because they gave me some glimmer of hope that I still mattered. I know that's not true though because these casual checkups they feel make up for it, I feel like wouldn't happen as much if they gave me a smidge of their time during the day. They barely text me but tell me they've been texting them all day. I'm the old toy in the back of the closet, the one with sentimental value but can't compare with the new and rarer models. It doesn't help I come with so many broken screws and bolts either. I just know I need to cut them off, but it hurts so much to lose more people and I can already tell I'm about to be alone again.