Relationship struggling & 27 weeks pregnant

My partner and I have a three year old, our relationship has always been rocky due to his past addictions but since being clean we have been doing well. However the last 6 months have been horrible. We have been together for 5 years and I’m currently 27 weeks pregnant with our second child and feel so alone. He’s never helped support our first born/support our family and I know it isn’t going to be any different this time around. He will spend all of his money on alcohol and cigarettes, be out all weekend every weekend partying then comes home and takes my money bc he has sent himself broke.. leaving me broke too and living like hell trying to keep our family afloat. I know I need to walk away, I can’t keep living like this. It isn’t fair on myself or our children and I can’t be living this same old crap with him when I give birth to our second. But I am so attached to him, he is all I want and I struggle the most the with fact I will be left with the family he helped create, having no one as I have no friends and basically no family. The family I do have live hours away.. all while he gets to live freely and do as he please with no care in the world. I’ve tried to hard to be perfect for him, I’ve spent over 20 thousand dollars on him in the last 6 months and it’s just “more more more” from him and he cries poor me and says he has it hard. I’m dating a huge man child and I can see through him completely but I just don’t know how to walk away!! 😭 I’m at my wits ends, I’m so so lost I don’t know who I am anymore. Does anyone have advice? Please nothing nasty I don’t think I couldn’t cope reading something mean.