It'd helpful to know what was going on in your waking life, because that is what generated your dream. But the symbols provide some clues.
Because the dream involves your children and their father, it's likely to relate to family issues. Feelings are never disguised in dreams, so how YOU felt IN the dream reflects how you feel about its subject in your waking life. My guess is that you were concerned about your kid's distress. Could it be that you are concerned about your kids in the aftermath of the divorce from your children's father... and the "death" or change in you since then? There's additional imagery suggesting that you feel that the road ahead is "dark" and that communication (represented by the IPhone) may have gotten away from you (maybe even lost "on the ground.") It's hard to say who the "two guys" might represent... could they be classmates or, if they were older, they might have a connection to their father(?)
Here are links to the definitions of the symbols which should help you fine tune your understanding of the dream:
darkness:
dreamdoctor.com/dream-dictionary/definitions/darkness.html
phone:
dreamdoctor.com/dream-dictionary/definitions/phone.html
dead body:
dreamdoctor.com/dream-dictionary/definitions/dead-body.html
death:
dreamdoctor.com/dream-dictionary/definitions/death.html
murder:
dreamdoctor.com/dream-dictionary/definitions/murder.html
You mentioned 'murder' in the title of your post, and if you feel that was the situation, it's important to take note of its meaning... that you felt that someone wanted you out of their life... your ex, for example?
The important thing to realize is that your dream is an expression of your feelings about your waking life. In this case, it would appear to reflect your sense of your kids' experience of you and your situation, given the events that have occurred. It doesn't mean that their experience is as you've dreamed it... it's your perception. Given that and your obvious concern, you might want to check in with them... even ask them about their dreams. Once you do, you'll have a better idea of how best to help them.
If you get a chance, please let us know what was the catalyst for your dream, so we can learn from it, too.
Thank you and good luck!