Do I break up with him?

I know I posted this before but I need advice. So my boyfriend and I have been in a long distance relationship for 8 months now. He kept telling me he's coming back soon. Six months ago he said he would come back in November. Then he said December. Now it's January and he said he would come back in February.

He kept changing the time and I don't know when we would be together again. I'm in New Zealand and he is in England. I am in uni so I can't just move there.

He said he has ADHD which causes him to be really bad at planning things ahead. When he bought his flight to England it was pretty sudden. He just bought a one way ticket and told me he was leaving in 3 weeks.

Now I am not sure if he's even coming back. What do I do?

Lately I've been asking him more frequently and he said that I'm being clingy and selfish because I keep wanting him to come back for me. I just feel awful waiting around with no certainty. When I said that he would always say "Well nothing is certain anyway, I could die tomorrow. You could die anytime too"