not a good girlfriend

My ex currently moved his girlfriend into his moms house with him. She was homeless and was living in a shelter. She has no job, no license, (due to a DUI) and she has her ex husband rasing her 5 year old son. I also found out that about a mointh ago she whet to AZ to pick up a shipment of pot with a older man, altough nobody ever got caught (so i cant prove this)
My children use to go to there dads every other weekend until i found out that the 5 of them would all sleep in the same room. Him and her in the bed and my kids on a air matress or the floor in the basment. My kids don't mind her but they do say that "daddy always does what she wants to do" I have stopped the over nights but he still gets them during the day on his weekends. I have contacted a Lawyer that told me that I had every right since i have full physical legal custody but i just want a second opinion.