breakup advice- warning it's pretty long!

 We got together when I was 17 and he was 18 and we have been in a relationship for 7 1/2 years. We have 2 children together. Things were never perfect, we did fight a lot but always seemed to move past it. This time is completely different and I don't see us pulling through. He left a few days ago but this has been going on for a few weeks. I haven't eaten much and have dropped 2 dress sizes. But every time I eat I feel like I'm going to throw up. I'm sleeping but not much. I love him, he is the only one for me but now it's time to focus on myself and our children. I'm just not sure how to start healing, my kids need me to be strong now, but I feel like I'm slipping through the cracks. How do i get over someone who owns my heart? Thanks ladies sorry for the novel.