Need advice please.

Sam

So I've been with my so for a number of years and we have a 15month old together. But our relationship has got bad to the point where I'm not happy. He pretended to be asleep at nights for the first 4months of our daughters live just case as he said in an argument one day he couldn't be bothered to get up to her. Well I do everything and I mean everything. And it's got to the point where when we have arguments I just agree that I'm wrong even if I'm not and simply try to stop the argument anyway I can all the while he calls me a Moron or tells me to grow up but yet at the same time he's says these things in a childish wingy way. I have sex with him as little as possible as I'm really not into him anymore but when I do try to break it off I always get threats of you'll never see your daughter again cause when I have her I won't give her back. And he throws in my face that I'd struggle without him as he's the main Bread winner. But I know it would be difficult but I also know I'm a strong woman who would be able to cope with it all problem is I work part time as a steward so I'm outside with the public alot and I met someone who I really like and they like me and we've been sexting the last few days and I really like this person its just I don't know what to do now. It won't look good if I end my relationship now and get with another man but I'm also worried about ending my relationship in general anyway because of the threats of him taking my kid for no reason. I'd like to add that he's always been jealous of the bond me and my daughter has, she does prefer me to him but that because I do more with her. My daughter is always my priority and I'm more then happy to be on my own I just don't know what to do my heads all over the place.