Should I stay in my marriage?

I am married 11 years but am not happy. I have 3 young children ages 5-9. I am not fulfilled by my husband. I want to leave the marriage but I have no where to go. I am a stay at home mom with a home business. My mother will not support me in any way even though she could if she wanted. She doesn't want the burden. I have no one else. NO other family or friends. I don't know if I left and went through the hell of leaving if I would find someone else out there who was more compatible with me. My husband and I both love our children but argue over little things. We should never had gotten married. We are two very different people. He is laid back and passive aggressive and I am more outgoing and love to enjoy life. I really want someone who is passionate about life who would make me smile and happy. My husband brings me down. He is a bit of a manic depressive. His mother is like that and I don't think he knows how to be happy. He is a real downer. Before I married him I had tons of friends and enjoyed life and had tons of laughs. Now I am so bored and lonely. When he is in the house, I can't wait for him to leave for work. I just want to be alone. He also hangs around the house all the time. I never have an empty house. He goes to work at night and is gone only when I sleep. When I wake up he is there all the time. I feel smothered. I like my alone time and feel like I am losing my mind with him home around all the time. Should I leave for maybe something more passionate or am I dreaming and should stay in my stable marriage?