Boyfriend won’t let me leave. Advice ??

So I’m 17. My boyfriend well (fiancé) and I have been together for two years . (15 years old) we have a one year old daughter and we live together. I moved in with him and his family in September of 2017. The first year of our relationship was bad. He treated me like shit everyday, tried breaking up with me everyday. Then towards the end of May 2017, he suddenly wanted to have a break. I found out that he cheated on me by asking some girl for nudes then a few hours later asked for a break. During this like month long break, he was texting other girls, trying to date/ fuck other girls, etc. (I didn’t find out about it until February 2018) Anyways , we got back together July 4 of 2017. I moved in with him September 1, 2017

& had our daughter September 12, 2017. Skip to a year later , we’re seniors. September 2018 was a hard month for us . We argued a lot. He was barley with me and our daughter and we only really saw him at night. Then end of November comes, and I get a five paragraph long text message with screenshots about how he’s been asking to fuck all these girls and lying to them that we weren’t together . ( also, during the time he was doing this he wouldn’t let me go to school, but he always went to first period which is where all these girls were in) my cousin even caught him in the car with one of these girls a day after our daughter’s first birthday . (September 13) I confronted him about what almost everybody in his first period was saying and he kept lying to me that, it’s not true etc. ( he’s really manipulative but I don’t believe him.) so basically everybody in his first period turned against him and he doesn’t go to school anymore . ( we also switched to online school.) his friends (guys) also came to me with screenshots about him trying to get with other girls and talking to them about other girls. I tried breaking up with him but he restrains me in the house and threatens me about how I won’t be able to keep our daughter . He also won’t let me break up with him by telling me “ no we’re still together” etc. I don’t know what to do. When I try to leave , he blocks the door or forces me to sit on the bed which results in us having a fist fight and him basically leaving me in a chock hold and saying that he’s allowed to do this to restrain me . When I leave to my parents house to get away from him, he goes to my parents house and waits for me . I don’t understand why he cheated on me with other girls but still wants me in his life. Maybe it’s because all his hoes and friends turned against him but he won’t tell me the truth if he cheated or not . Whenever I try to leave he threatens me with me not being able to have my daughter or that I won’t be able to live without him. It’s sounds easy just to get up and leave but he’s very controlling and I don’t have help from his parents when he’s doing this because they don’t want to get into our arguments. He’s also 17 like I am but younger than me by 13 days, but keep in mind. I’m like 5’2 and he’s 6’1 so he has all the power to stop me from going somewhere. I tried telling him I don’t have feelings for him anymore and he just said “ no you still do” I live in Colorado but I don’t really know all the laws and what not. I don’t know what to do or how to leave without him finding me and threatening to take my daughter away from me . He also doesn’t help with our daughter . Yeah , he and his grandma provide for her because I don’t have a job but whenever my parents try to help buy her stuff , he doesn’t want it because all he wants is money so we can buy it & he doesn’t watch her. He doesn’t feed her, change her , bathe her, put her to sleep , etc. I do all of that, but he still tells me that if we break up , the court won’t let me have bella and will let him and his grandma keep her .