Anxiety breaking relationship

I have really bad anxiety. Like really bad.

My boyfriend of 3 years has things in his life that makes me anxious from time to time. Like he is best friends with his ex, they have dogs together and I accepted that but I just need reassurance sometimes. We had a massive row because in 3 years I was finally allowed to stay in his flat, but he said it felt weird. We moved past it.

Last night I had a horrible anxiety attack and needed reassurance.

I just said I was scared he didn't love me anymore and I was worried he was finding comfort with someone else.

Because we have barely spoken, I maybe see him every couple of weeks and sometimes it feels like he isn't trying. He sees his ex and the dogs more than he see me. I didn't say this to him, but he flipped out saying he was just getting over our last argument and I'm putting him through this. Then said he doesn't know if he can do the relationship anymore.