Do you know what the relapse rate for meth users is? 92%. Only 8% of people who use Meth stay clean. The drug causes major damage to the brain and to the body and that doesn't even include the damage from the risky behavior associated with Meth use. A specialist in Meth addiction (I can't remember his name) believes meth addicts need to be in a specialized meth treatment program for a minimum of 12 months in order to achieve success.
Second chances? That is a decision only you can make. I will say that he needs a professional treatment program, he cannot do this on his own.