Toxic guy friend

I used to be friends with this guy a few years ago. We were getting along great at first but after a few months, I realized something was off with him. I would leave our meetings drained and upset, on social medias he would encourage his friends to put me down when I was giving my opinion and he would also regularly list me every reason about why I would not succeed in my projects or what could I do instead of doing what I was dreaming of.
I think I was irritating him because I was about to do (and I did) something he was dreaming of and never had the courage to do himself. He lied to me many times, on small and big stuff, he would copy my lifestyle and pretend he always used to do that or love this… Very immature, very exhausting.
I took my distance, and at some point I just got very angry with him because of another lie that was just so big and showing so much how stupid he thought I was. I blocked him everywhere after explaining why and how sick I was of his behavior.
He came back after a few years, apologizing lots, and seemed to have changed a bit. We did not become friends again but he would regularly come to me on internet to chat (I live in another country now). At some point I deleted all my social medias to stop losing so much time and focus and just disappeared from him.
A while back, I opened a new account on FB, just to share more easily with my friends and family. He quickly found me, added me and started to try to talk to me again regularly. I replied but I stayed cold and evasive. A few months after, I could sense with his questions and wording that he was again waiting for me to fail to make himself feel better. The fact that he is even virtually in my life puts so much stress to my already complicated situation.
I want to cut ties, forever, but I don’t know how to approach it. Should I block him (but I’m staying on FB and I know he is going to open another account just to come and talk to me, he already did that once), should I tell him that I want to stop being in contact with him before blocking him, should I explain why ?
He is just so toxic and so incredibly manipulative. And I’m sick of FB showing me each time when he comments on a public page and he bullies random strangers, he really has a serious problem.