Trouble making friends

im 17 and I've always had issues with making friends even when it came to elementary school, etc. whenever I made a friend they always ended up being awful to me and being manipulative, i feel like im somehow just a magnet for those kind of people. So I've pretty much grown up being incredibly cautious around people and when someone treats me nicely and doesn't pity me it's like my whole world revolves around them, in the same time I feel like I switch up on people incredibly quickly when something bad happens now.

I recently cut ties with one of my best friends back in November as she would encourage me to do things to myself, etc. I realized even after I cut ties with her she managed to find someone straight away, which I'm still destroyed about as she was pretty much my everything.

so my anxiety around people replacing me feels so much worse again

I do have another close friend that I've been friends with for a few years now and I haven't had any issues with them which was really surprising to me–hes the only person I have left and the only social contact I have as I'm home educated and I don't have a job, etc. ive never thought badly of them but recently he's made this online friend and it's like he's changed. We would call everyday and text, we'd take turns on texting first and stuff but now he has this new friend and we don't end up doing that anymore.

I'm convinced that I'm no longer interesting to him and that maybe he got bored. He calls with that person full time now, it's not like he does anything else and doesn't even bother inviting me or texting me first anymore. Doesn't even try to hold a conversation when I try to text and it hurts so much.

I've tried speaking to him about it but his behavior doesn't change, he says it's 'okay, ill never leave you' then does nothing about it. So I tried getting along with this new friend of his, we all called together. The entire time it felt like they were babying me and leaving me out, as it I was something fragile and sensitive?

I can take jokes fine and stuff like that but it was like he was treating me entirely different like he used to, he was acting completely normal to his other friend. I just don't understand what I'm doing wrong, I've done so much for him. I've always been there when things were rough and id try to help with things, i try new things if he wants to do something with someone. I don't understand why people leave me when I try so hard, it's like im so easily discarded and it makes no sense. I find myself starting to hate him and become obsessed over what he's spending his time with and i hate myself for that because I know it's wrong. it feels like he's completely betrayed me after he found someone else, I know him in person as well and somehow he prefers this new online friend he only started speaking with a few weeks ago.

I'm scared that maybe it's all my fault and that maybe im being controlling but I'm genuinely terrified of losing him. I've been losing sleep and it's effecting my day to day life to the point im barely able to get anything done since my mood is either frustrated or upset

I feel so much frustration but in the same time I can't imagine myself ever leaving him