You phrased it as Trump burnt the bridge. Did you watch the debates? Trump practically asked Cruz to be his running mate, but needed him to clear up the birther issue. Trump is in it to win and isn’t going to take a risk on the birther issue. Ted failed to get it cleared up and instead tried counterattacking. At this point, it will be a stretch for Trump/Cruz to make up to be on a single ticket. And I’m saying a stretch as Trump is known for not holding grudges. If the bridge is burnt, Cruz did the burning.
Why would Trump practically ask an “obviously ineligible” person to be his running mate, putting his campaign in the general at risk?
Trump isn’t saying “clear it up” - Trump is calling him “a Canadian”. He says its clear. You are simply misrepresenting him.
Maybe Trump doesn’t hold grudges because he really doesn’t mean much of what he says, including his attacks on others. Just saying what he needs to in order to win the deal.