Long rant- becoming a single mum

So me and my partner are 19, still living with our parents and have a 7week old baby together. I pay my share of rent and bills for my parents and buy ALL of our babys milk, nappies etc. My partner works a normal 9-5 job and i would bring our daughter to see him after work for a few hours before going home again. We all stay together at the weekends. The thing is he literally does not help out with the baby at the weekends at all( i dont expect much during the week because he works) and during the week when he sees her he holds her for about 5minutes before putting her down or handing her back to play xbox for the rest of the time we are there. He also drinks every single day, i wouldnt mind a few beer here and there but it is hard liquor almost every single day with me and his baby sitting there with him or he would tell me not to come down because he wants to go out with his friend and drink. I finally confronted him about everything and he broke up with me saying he is allowed a life and sitting in with me makes him miserable and unhappy and after 3 years together he hasnt loved me for months, (which shocks me as he says it every night before bed without fail) and has been already talking to some other girl after all this just happening only last night. Was i too hard on him about not helping me out( he says he works and thats enough but he doesnt help provide for our child) i have felt so irritable and alone and overwhelmed since my baby was born and i feel like ive became someone completelt different to who i was before and hes just fallen out of love with me. I feel like the whole.situation is just immature but i dont know how to move forward and be mature about it for the sake of our little girl.