I think it's interesting that you view anger as a disproportiate response.

From how I'm hearing this, you had a close, intimate session with your therapist that meant a lot to you.

Then you sent him something important to you, expecting minimal acknowledgement.

Then he doesn't reply, at all - which any reasonable person would perceive as being blown off.

This would be hurtful in any close, intimate relationship.

Certainly worth discussing next session. There is more than likely a reasonable explanation I.e. a missed email or a hectic schedule.

But again IMO, I don't see this as an over-reaction.