Mexico import vehicle permit

I need some advice. We drove from the USA to mexico about 6 weeks ago going to Belize. We are driving back from Belize and are in Villahermosa mexico now. We were stopped and told we did not have a (TIP) temporary import permit for our vehicle. We were told they could impound our vehicle and throw us in jail. They finally let us go and told us to go to the border between Guatamala and mexico as that is the closest customs office. It is about 3 hours away. When we left we made a decision to not go to the Guatamala border we continued on to Villahermosa. We are in a hotel and I have done my research. Yes I understand we should have gotten one when we originally crossed into mexico in McAllen tx. We didn't. We drove all the way through mexico, got stopped over 9 times and never once were questioned about a temporary import permit or told we need one. So now do I continue to McAllen tx without the permit and just try to get back or is this really serious and I need to go to a customs office on the border and get one?