You should quickly file a complaint in divorce together with a special relief petition requesting a freeze on all accounts and that he provide an accounting of any funds he has removed from any accounts.
Ince the mother has not made an attempt to maintain a relationship with the children for a period of six months or more, you may file a petition for involuntary termination of her parental rights simultaneously with a petition to adopt filed by your wife.
If your father died without a will, then you are entitled to a percentage of his estate under intestate laws. If he did have a will, his estate will be distributed as he wished pursuant to his will. Typically when people are married any real estate is owed by both spouses together, so when he died his current wife would now own any real estate that was deeded in both names. You can check with the register of wills in the county where he resided at the time of his death to see if a will was filed.
If you don't know his whereabouts, you can hire a private investigator to do a search for him and then, provided he remains unfound, you can attach the report to a petition to serve the defendant via publication in the place of his last known address. Then if you publish notice to him in the paper or other periodical designated by the court, he will be deemed to have been served even if he doesn't actually see the notice and the case will proceed without his involvement.
You have to serve him with the divorce complaint within 30 days of filing or else you will have to reinstate the complaint and try to serve it again within 30 days. Once it has been 90 days since he was served (and proof of service should have already been filed), then if there are absolutely no economic issues to resolve, you will each need to sign and file an affidavit of consent and waiver of notice and then a praecipe to transmit the record can be filed. There is no reason you would need...
Adultery is relevant for the following things:
1) To give you grounds for divorce in the event that your spouse will not agree to a no-fault consent divorce and you don't want to wait two years to obtain grounds for divorce under a different section of the Divorce Code;
2) You make less money than your spouse and have been the dependent spouse and you want to make a claim for alimony;
3) You make more money than your spouse and your spouse has been the dependent spouse and you want to...
If there is a custody order, she cannot unilaterally decide that she no longer needs to follow it. If there is no order, then your husband should file a custody complaint ASAP so that he can obtain an order that she will have to follow.