This is exactly the problem with fake news. It sticks around, and you've been caught by it. It seems likely that this fake news has influenced your ability to make rational decisions about how you vote, etc. This is a huge problem for democracy.
No he did not withhold military aid from Ukraine. In fact in the initial offensive, the javelin missiles that they were effectively using against Russian tanks came from the Trump administration. And in fact Trump was highly critical of the previous administration for "only sending blankets", which was something he was called a hawk for.
AND NOT ONLY THAT but one of the major points of Trump's presidency was criticizing European/NATO nations for not spending enough on their defense; specifically warning that Russia was going to use their dependence on Russian natgas, and lack of military spending, to Russia's advantage.