The problem with WhatsApp is the other person can see that you are typing when you are in a chat with them, and if you stop typing then they know the message isn't for them. (Just a heads up for why he is so unreasonable when you are talking to other friends).

That being said, you deserve better than this. My guy sees me typing to other people on WhatsApp, (that's how I know other people can see the typing), but it doesn't bother him at all. This is a small issue, (not to diminish or downplay your feelings), but this shouldn't have escalated to the point where you feel its emotional abuse.

Small things usually lead to bigger things. Just be careful.