My prayers are with this family. I have seen what gambling can do to people and their families. Obviously the child is the number one importance. On a practical side, I can tell you this, after working at IRS for 15 years and being a self-employed tax consultant, there are ways of working with the IRS. There is something called an Offer-In-Compromise that they may qualify for where a deal is made with IRS to pay a reduced balance or if that doesn't work there are payment plans. The IRS offers a taxpayer advocacy office in most states and their web site may be able to give this family guidance. It won't fix the bigger issues in your lives, but it may relieve a little of the preasure. I have prepared many offers that have been excepted where huge tax bills have been reduced, others the IRS has not agreed to but payment plans have been worked out.
Again,my prayers go out to this troubled family and healing prayers for your son.