Hi, i impurity. Welcome. Sorry for your pain.
Sadly, yours is a pretty common story around this site. A promising relationship heads south fast due to addiction.
As Ann said, none of this is on you, and there is really nothing you can do, save walk away from this sorry, sorry man.
You and your child should NOT be around drugs. It is a recipe for disaster.
Though you are very sad and wishing you had the good man you fell in love with back, you have dodged a substantial bullet. Life with an addict is the hardest thing there is.
Please protect yourself and your finances. Do not allow him back in if he comes around--and he very well may. Cut all ties. He is not good for you.
Sorry to sound so abrupt. I wish you the very best and hope you will keep posting. This is a supportive site. Lots of experience, strength and hope.
Peace.