So lost on baby daddy

So my baby daddy and I split up a little over 3 weeks ago and we are having to live together (I’m moving out soon) anyways we have a 1 1/2 year old daughter and let me just say up until this point he has been an amazing father. I do believe he has gotten into the drug lifestyle due to things I’ve seen and people he is hanging around. Well every time now he leaves on the weekends to go party when here soon once I move he will have her every weekend. When we are at home he sits on his game and constantly handing her back to me instead of spending time with her. He will make up excuses like “I don’t feel good” to get out of taking care of her. Like if I’m sitting on couch he will bring her over to me instead of playing with her when he hasn’t seen her all day. I’m really upset because he was such an amazing father before and now I’m so lost on what to do about him? I know there’s not much but I’m lost in this world. It’s been three weeks and this whole time he has done nothing but come up short as a father. Us doesn’t have to do with her at all I don’t get it. Also he was saying he wanted 50/50 when we first split up and now he’s just kind of falling off all together. He will be like “love you” but I can tell the emotional connection just isn’t there like before it’s al changed…