Jenelle Evans and David Eason suffered a major court defeat Tuesday, when a judge ruled they will not regain custody of their 3 children ... and they will have virtually no face-to-face contact for the time being.

After 4 days of explosive testimony, in which Jenelle, David, Kaiser's dad Nathan Griffith and others testified about problems in the home, the judge decided there were serious issues with Jenelle and David that put the children at risk.

The trigger for the hearing was David killing the family dog earlier this month. As we reported, Child Protective Services ordered 4-year-old Kaiser to stay with Nathan, 9-year-old Jace with his grandma, Barbara, and 2-year-old Ensley also with Barbara.

Sources connected to the case tell TMZ, for the time being, Jenelle and David can see their kids only once a week for an hour with supervision.

As one source put it, "It's all David's fault."

Another source says the judge laid out a number of steps Jenelle and David must take in order to regain custody, including parenting classes, counseling and weekly drug testing.

And yet, another source told us Kaiser was "extremely fearful" of going back to the family house and claimed he was mistreated by David. His concerns were brought up in court and we're told affected the judge's decision.