I don't mean to sound flippant, but sometime it helps actually act out those feelings in a safe way. Scream obscenities into a pillow. Beat the crap out of your sofa. My T kept a nerf bat (sort if a foam rubber bat). Her clients would beat in her sofa when while yelling what they were mad (if they knew) about until they felt better. I tried and found it deeply satisfying.

It's ok to be angry it's just an emotion. Sometimes we don't even know why we're angry but that ok too. Sometimes it's just an accumulation of life in general especially when we're suffering from the chronic illness of MI.

Also there is a cuss thread in the forum, you can there and cuss your head off. you don't need a reason