Stbxh left in September and pulled his new girlfriend in October in front of me.For what ever reason stbxh meet her kids within weeks and has been staying over up to 5 times a week. He hasn't had either of our kids at his mother overnight as promised as it would ruin his social life . He works two weekends out of four and her kids go to there dads every other weekend . he admits he doesn't need to buy or rent as his partner has as home. However our 14 year old son has taken it all badly and I have found evidence of weed , smoking and drinking .I have up to now included ex But ex has buried head in sand ..I have had contact with police, SS and school. Been round local shops with his picture. Driven round streets at midnight etc. All this time ex has done nothing but get his feet further under his partner table.I have finally gone non contact with ex and told him its down to his lack of support .He is acting hurt and shocked. He has never texted or asked how the boys are. pls help me be strong and offer advise.thanks.