Did apartheid South Africa have a right to defend itself? Did Rhodesia? Did French Algeria?

No. Regimes like these have one right: The right to be thrown in the dustbin of history and to be replaced by a more just order.

Israel is making it's own decisions and will happily shrug off any criticism from the Western powers

There has been zero sincere criticism from the West. If you circumvent Congress to give Israel more money and openly state you are unconditionally supporting it, I don't buy it if you leak a story about being furious with them behind closed doors. You shouldn't, either.

Why should they have a right to defend themselves? It would be more ethical if they all killed themselves.