How do I deal with feeling extreme abandonment when I fight/have disagreements with my partner? I relapsed today after doing so well! I try so hard to keep on top of my bpd but sometimes I just can't :( 

I just had a massive fight with my bf because he wanted to spend time with a friend for afew days on the weekend (our time that we have scheduled every week to see eachother)

He works until the afternoon and he lives about a hour away, so he comes to see me every weekend and we made that time for us. 

This week he wants to see his friends (male friends) for two days to do something (honestly can't remember what it was). Only now once I get upset does he say "I'll reschedule" but not prior. He said he feels bad to have to say no to them and he said he will tell them that he forgot. He says I'm being unfair. I probably was tbh. Plus I was really mean to him while splitting. 

I'm pretty upset that he didn't say no to begin with. I was late taking my medication today and so I had a huge outburst that came out of nowere. No I'm hypersensitive and super mad at him. I don't know how to calm down. This disoder makes everything feel like the world is ending. Like abandonment is real. And it's so intense. His right though. He should be able to see his friends on some weekends. I can't always be the centre of attention on weekends. He works most other days until the afternoon so it's fair that he has to also sometimes see his friends and family too on Saturday and Sunday. And that's vaild. But my bpd makes it feel so so painful.... How do I deal with this feeling?