My bf of nearly 2 years has been diagnosed with depression and prescribed anti depressants. 
I kinda 'forced' him into therapy because for the past few months he's not been himself. 

Imo, he left years of childhood abuse and neglect unchecked and a series of recent unfortunate events made him go on a downward spiral.

 The diagnosis didn't really surprise me unfortunately, but he took it as another thing going wrong with his life.

Even though my family and friends are pretty open about mental health, he doesn't have a good support system himself and he shuts down from me a lot and closed off his other relationships.

I've never dealt with someone with this level of depression and i don't know what to do.
We argue a lot and mainly because i try to help and insist he takes care of himself first. But anything I say he takes offence. 
I want to help but clearly I'm being overbearing. I'm scared to step back because i know he won't ask anyone for help and will only isolate himself further.

He's started on anti depressants now and we're on a time out right now for a few days. 

I don't know what's the right way to go about this?
I both don't want to abandon him but also i think i might be being too much?