Why cant i walk away?

Ive been w/the same guy for over 7 years, almost 8. We also have a 5 year old together, whom is going to be the 1 they'll suffer the most if i do leave. So do I, do i leave a man who never shows me in any way that he cares about me except when he wants , then he does a complete turn around & is the nicest guy. When he's not, he is dis-respectful & he can be so dam cold! He doesn't do anything with his son except play ******* video games w/him & when their doing that it seems like he's yelling at our son for not playing the game right. He also gives our son rides on the love of his life (at he time) his go-cart, which he literally works on 24-7. All day & night he's f**king around w/that go-cart. He doesn't do anything with me or our son together as a family, EVER!! He doesn't even barley spend holidays w/us. He doesn't ever take us anywhere, we never do anything fun. My folks have bought every single piece of clothing my son has ever had! & so much more! But ofcorse he doesn't acknowledge any of it! My folks have helped us out SO much & he acts like its nothing! I don't even know if he's ever even thanked them, for anything! He is a mean man with major anger issues that he denies. Yes he has hit me, & i told myself i would Leave him if it ever happened again, this last time was the worst & yet i still stayed! I don't know why & I hate myself for not being stronger but he's got a hold over me that i cant explain. The few times he's given me something (out of no where) he always took them back, other than that he never has given me flowers not even a card on our anniversary, all 7 of 'em! ! Actually he's given me 3 things for my bday & xmas that i was able to keep & all 3 were the same thing - a gift card, from the same store. Anything else he has given me he ended up taking back with out me knowing & sold whatever it was, spending the money on himself! He thinks im so ungrateful since he pays the rent with money that he doesn't have to do **** for! He doesn't have a real job & what he does do is nothing to be proud of! He blows hundreds of dollars on himself & his toys yet he cant even give me 200.00 for groceries. when I ask him for gas money, which he drives my truck whenever the hell he wants, he gets all pissy! I cook for this man everyday, i do his laundry & im always cleaning up after him because he doesn't do a dam thing around the house, He doesn't even throw his trash in the trash can, He's gotten so many parking tickets while driving my truck, that i have credit agency's after me now since he refuses to pay them! he's gotten us evicted or we were told to leave almost every place we've ever lived. He has literally almost ruined me 7 my life so why the **** cant i walk away? I know i need to leave him for the sake of my son but i don't have anyway, any money to do it! I feel stuck & strapped down without having any strength to brake free! I love the man he was when we 1st started seeing each other, but he's long gone & I know this. I guess i was just hoping i was wrong & that he would change but they never change, do they?? I know my son is going to hate me when we do leave because he wont understand, the thought of that scares me to death! My son is all i have & for him to hate me will just make it that much harder!! So please can anyone give me an answer ? can anyone give me any kind of hope? Im scared & I don't know if i have it in me, pathetic isn't it? & to those of u who are ready to insult me in anyway for being weak, just remember u haven't walked in my shoes, u have no idea how ive lived my life so don't say shitty things please, why would u want to shove someone down in the dirt who is trying to find away out of her situation!