How can I ensure that my ex gets only supervised visits with my two girls? He has recently threatened to take them and harm me and my husband. He has told my children lies about me and has owed more than $12,000 in back support. He just recently was awarded Social Security Disability for mental health issues. He claims that I will have to pay him back. I am remarried now and don't work because my husband supports my decision to be a full time mom and be involved with their school. He also lives in deplorable conditions and drinks a lot and smokes marijuana. Any advice would be appreciated. What exactly should I tell a lawyer when seeking to modify visitation.
Thanks.

You tell an Attorney exactly what you've said here and you bring your proof with you. Without proof it's "he said/she said."