Please help? First love was a narcissist

Hi, I'm new. I am in hell at the moment, in my mind and emotions, I am really suffering. The guy who was my first love, who I trusted, thought I would marry and be with forever I think is a narcissist. He has rebounded to another girl 22 yrs younger than him, I was 10 yrs younger, and I am just discarded. It's like I don't exist to him, not even a check to see if I am ok. He has just swapped her for me and carries on. I thought it would fizzle out and about 2 years ago, I thought it finally had, as he came back, but then he bottled it and went again, saying he'd hurt me too much, and now I am totally cut off. He doesnt know, or care, if I am even dead or alive.

This is really killing me. I think it's also because he was my first love, and I didn't do the boundaries right, he ended up breaking up on my birthday too, which I was so confused about. I've never heard of narcissism before, and never knew someone could have no empathy. Please help me, I am in turmoil, and my life is stuck. I don't know if I can, or ever will get over this, because it was my first love too. I went into depression and at the time he rebounded I finally accepted he was not coming back and got back to normal and then he came back, only to mess me about and go again and it sent me into depression again. Time does not seem to be healing me, I guess because I am so hurt and powerless, and thinking how did this happen to me, why me, etc. I am supposed to be intelligent and I'm pretty but he still did this, and I am abandoned and erased and it's hell.

Please can someone give me some advice, as I am stuck in a loop. I keep visualising them in the house I helped him with, she ended up moving in instead of me, I mean who does that? Also, when he came back I finally thought we could get back on track, only it didn't and he is still with her, now 4 years later, and I have been sad for all that time. I've been in counselling and still am, but it's not getting me unstuck. I guess cos I am gobsmacked at how this happened to me, and cant come to terms with this behaviour and someone doing this to me, and because he's my first love.

Any advice, I really need all your experience and advice? How do I get unstuck, and my life back, and my peace of mind back, my feelings, and normality, because right now it feels too much and like I will never recover from this. Please help me. :(