How do I know when too much crying and being sad becomes depression?

Decided to leave my now ex partner at 6 months pregnant. I don’t feel like I’m being loved or respected and that I’ve just become an option now. I haven’t seen him in a week spoke to him twice his phones always off only messages me at 4 am in the morning I don’t understand how a person can treat you like that and then say they love you

And how much you’ll miss them when their gone I explained to him that I miss him more than he knows now because he’s never ever there for me. I’m never gona stop him seeing his baby but I very much doubt he will stick around. Was this message too harsh? Spelling error I meant convince not conceive lol

I said I don’t want baby stuff because simply he’ll use this as an excuse to try worm his way back in, he spends majority of his money on weed, alcohol and gambling even though we’re expecting soon he’s bought one piece of clothing so I know I’m going to end up buying everything with family’s help anyway

If he does buy her things I will obviously accept them but I’m trying to make him understand that won’t make me take him back

And don’t bother commenting that I’m using my child as a pawn that’s not the case he knows he can see his child whenever he wants and if he chooses not too I know his family would love to have her.

The breakups still very fresh and I understand I need to grieve and give things time before making rash decisions but I don’t want to fall into a path of depression so how do I know when to seek help or if it’s a normal part of heartbreak