He is scared. He doesn't want to quit for himself as he said he is doing it for you. I know he initially said he wants it, but addicts lie - lie - and lie some more. That is what we do when we feel threatened. It sounds like he is still a long way away from truly wanting recovery.
Being on the fence is not a good place to be and you can expect more moodiness. It will actually get a bit worse when he quits because he does not have his crutch anymore. So yes you can probably continue to expect more of the same until he makes a real commitment. It doesn't have to be meetings, but seeing a therapist or going to rehab (inpatient or outpatient) and talking to other recovered addicts is important as he tries to figure out how to live day to day without falling back to drugs.
It is tough because you have a child together, but you need to be prepared to move on with your life without him. I am not telling you to run, but am warning you you are most likely in for a wild ride and not a fun one at that. My wife went through 5 years of hell with me. I would get her hopes up for a few months only to smash them over and over again. It was like grieving a death again and again. All of the manipulation and lies and disappointment mess up the partner or spouse almost as much as the addict. I suggest you try Alanon or a therapist for yourself. You don't deserve to have to live like that. Sorry for your pain. I hope it works out, but the odds are against you.