How to help my boyfriend

I have been in a relationship for the past 6months, my boyfriend is on the process of getting a divorce. He was maried for 12yrs, has 3 children with this person. Although they have been separated for a year, and she has moved on with someone else, that has affected their children, and my boyfriend feels that if he brongs them around me, it would cause even more of a trauma to them. When my boyfriend was married and living with his ex, I dont think they were happy with each other, but my boyfriend stuck around for the children. I know that a 12 year marriage is not forgotten over night, but how do I handle those days where my boyfriend is depressed for putting his children through this burden? How can I tell him that Iam here to help him tell his children that Iam his girlfriend and that I want to be a part of their life?

The divorce is in its third month. I completely understand where he is coming from, and I will wait for him to be ready to tell his kids that he has moved on, but at the moment what can I do to help him,emotionally. I have meet his kids but I was introduced as a high school friend, and the times that we did hang out with his kids, I always had my sister with me. I know his kids aren't dumb, they can kind of understand who I was...but in front of his kids we never kids we never held hands or kissed. I tried to mingle with the kids, and they were nice and responded me when I asked.