I was just reading about your in-laws --and the fact that they are supposedly strong Christians --even ministry staff with their church is crazy! Their reactions are horrible. NO REAL CHRISTIAN has that kind of response. Divorce is NOT acceptable to a serious Christian --and your in-laws should be doing everything possible to support you and your children and to be correcting their prodigal son. No ---there is something very wrong here. These folks are as fake as they can be ---and it sounds like the parental behaviors when your H was a child were far from what was needed or required for an emotionally healthy, mature man.
I am so sorry about all of this. But this is NOT too big for God. Sadly MLC will expose a lot of hypocrisy --not just within the prodigal spouse --but with other family members too. You and your family are in my prayers.