The most baffling thing here is the people turning out to white-knight on behalf of someone who is engaging in truly toxic behavior. Let's walk through this.

OP enters a party severely under-geared, including wearing equipment which doesn't even scale with his role. This is in a level 69 Dungeon, and OP has a job at 80. It's safe to assume they know better.

Upon wiping, OP takes it upon themselves to offload blame onto the healer.

The party, seeing this toxic behavior, moves to defend the healer and quickly dismisses the OP from the duty.

OP, unable to let the issue go, decides to make a public post on the forums decrying himself the victim and becomes hostile with people who are trying to point out that he was in the wrong.

Offloading blame for your mistakes onto another person is very toxic. Not only are you refusing to accept responsibility for your own oversight or shortcomings, but you're actively harming and gaslighting someone else in the process. You're attacking someone else's self-confidence for the sake of preserving your own, despite being in the wrong.

What exactly is worth defending about this situation?