Yep. Was when I divorced...and one of my kids is a juvenile diabetic. As my ex didn't want to share custody, I got full custody, which was just fine by me. So I had two kids by marriage to raise by myself, plus a few friends of theirs who needed a little help in the parenting department.
As a single parent, the hardest part was realizing that I had to be there. Every day. After work...which meant no nights out with the coworkers at the bar or on the golf course or the bowling alley. Weekends spent with the kids doing extracurricular activities and homework. Vacations ditto. I had to be at every parent/teacher conference or school event my kids were involved in. I always have had an open door policy with my kids, to this day they can talk to me about anything...and they know I'll listen. You also have to be honest with them when they ask questions about their parent who isn't involved in their lives...because they have a right to know. Was I perfect? Heck no. But I did figure out what it takes to be a good parent.
If you want your kids to grow up on the straight and narrow, you need to be an active parent. Be home. And pay attention. You owe them.