Going too Far

My bf and I have been together over two years he has three kids from a previous marriage and a relationship. Two of his kids are teenagers close to 18. Constantly theres always drama with the kids doing teenage stuff. Of course my bf confides in me with all the drama. At times things get tense between us based on my opinion(keeping it real) I give about the situations...How can I give opinions without being harsh or should I just simply say ok and stay out of it. I want to be supportive but also dont want to over step my boundaries and cause arguments over his kids.