You certainly can trust Cruz to keep his word.
https://www.youtube.com/watch?v=Ty1eETVIFMs
There are certain levels of conduct implied in a presidential campaign. Among those, no attacking wives, and extended family. Slander is frowned upon. After the avalanche of lies and attacks from the Trump camp, I would have felt him justified at some limbic level to just walk up to the microphone and wish any number of ills on Trump. Instead, Cruz kept it classy, about the country (AFTER congratulating Trump) and refused to kiss Trump's ass by simply not doing so.
But I suppose, that despite reneging on that promise well beforehand (after those lies from the Trump camp were well under way), that the Trump people are still desperate to justify having called Senator Cruz "Lyin' Ted" for months. You still don't have that justification.
Look now, at the new king of the GOPee. Donald Trump. He isn't an 'outsider' now, he's their poster child.