How can i ask my daughters father's family too back off without offending? 31.5wks pregnant?

when i fist told my babys father i was pregnant he was brilliant and even asked me to move in with him. i moved very far from home and lived with him and his family, however things soon went sour and i got very hurt and messed around, he soon told me he wanted me to abort or giver her up for adoption and he didnt want to be a dad. his family were extremely upset at him. his family have always involved themself in our issues and more often than not make things worse. Now i have moved back home and have been getting used to things on my own. i recently got a message from my babys father asking if he could be at the birth, i asked him why and he said he 'thinks' he feels 'okish' about things now. hes constantly high and seriously immature. i think he is only asking to be there because his family are telling him he has too, and i dont want him to see out daughter because he feels obligated. i have given him chance after chance to get involved and he hasnt even now hes messing about with weather or not he'll come and help me after she's born so i know his heart isnt in it. he also ignores me a lot and then makes up excuses wich are lies. Although his family are moderatly nice i feel like they are too involved, often i cant breathe because i feel overwhelmed by how involved they are. And honestly, they are quite disfunctional. I feel like both myself and my daughter would be better off without him or his family in our lifes , theres too much drama in their life and i really just want to concentrate on being a good mum. I wouldnt stop him from seeing him if he was behaving appropriately and responsibly and wasnt going to be damaging too her but right now hes not. regardless i will still let him have controlled visits etc but i really dont want his family around, i feel they make things worse and i dont know how to tell them without offending them?