should i leave we have been arguing a LOT lately and VERY bad ones i dont feel as though i am in love anymore?

i am to worried to leave cause there are two children involved my three year old from a previous relationship who adores him and just had a baby on labor day, but it is constant fighting and i mean VERY bad in front of my three year old, i dont want him exposed to that i was and said id never put my kids through what i went through. i dont even curse in front of my son i dont want him seeing the things he sees then he goes to his dads and tells him. i feel selfish cause i am still with him and i feel i am in a love less marriage i have asked him to leave several times but he wont i can say he is THE BEST father i have ever met but i also think he can still be that if we are not together but, my three year old would never see him again and i would be even more broken hearted cause i know how much he cares for him. i just have so many mixed emotions, our relationship went down hill just recently and very fast when we got in a fight and i took my son and stayed over night in a hotel. i wont talk to him or let him touch me i rezent him. my feelings changed for him over night and VERY fast. im not perfect i have my faults but, he seems to forget what has recently happen but i cant and he doesnt understand why i feel this way now..................