I am sorry you feel so alone. I know how exhausting it is bringing up a young baby and you’re having to deal with your partner’s addiction at the same time. Your partner doesn’t seem to want to accept support but maybe you could use some for yourself. The Icarus Trust is a charity that supports the friends and families of addicts and it might help you if you make contact. We have experienced trained volunteers who you could talk to which might help you to see the way forward.
You can contact us on help@icarustrust.org or visit the website http://www.icarustrust.org
I do hope you get some support. Good luck with everything.