You said he didn't seem to send me a group message. Should I reply?

If you want to go back, you don't have to go back if you don't think it is necessary.

If he sent it to you, then he should return it politely.

If it's not a mass message for you, you can watch it.

It's simple. Don't think too complicated. If you are not sure, you can also contact by phone, greet each other and contact your feelings.