I've also been through therapy for years, although not currently. IDK whether it's true or not but for me personally I feel as though therapy can deteriorate from a short, sharp, beneficial "intervention" (which is very helpful) into a malaise of relating ones problems to a friendly ear (which is unproductive) ... but I digress.

This sounds to me like one of those problems which is a symptom potentially caused by a myriad of different issues, and as such has no specific "cure". As you've said it's "accumulated stress", which is another way of saying the same thing. I feel like I run into this type of problem a lot: the solution is really easy, I just need to do better at life!

My one suggestion would be to look at therapies for anxiety, since anger and anxiety are commonly symptoms of the same problem. There's two common therapies for this.

Firstly Cognitive Behavioural Therapy (CBT) - figuring out why your thoughts follow the patterns they do and as a result, learning how to change those patterns. This is hard work. It's a bit like going to a gym. You need to set aside time for several sessions a week of examining the parts of yourself you've been trying not to think about your entire life. The gold standard for DIY CBT is "When Panic Attacks" by David Burns, alternatively "feeling great" by the same author. He has a podcast also. I know the dirty dog feet was just an off hand example, but to continue that example you might discover that you have a deeply held belief that people who have dirty houses end up sad lonely and unloved, a potential solution might be to tell someone who you feel is happy and well loved how difficult it is to keep a clean house - inevitably they will agree with you and tell you how hard they find keeping up with their chores.

Secondly Acceptance Commitment Therapy (ACT) - accepting that stressors will always be present, understand that they're harmless, fleeting thoughts, and committing to a course of action that is more meaningful than simply "avoiding stress". Author Steven Hayes is the gold standard here but personally I find his stuff too heavy. I quite like "DARE" by Barry McDonagh, basically ACT but more easily digested. This one is more readily applied "in the moment". It takes practice but there's no sitting and pondering one's soul so-to-speak. This is very difficult to explain in a sentence but you might acknowledge, in the moment, that dirty dog feet are infuriating, you feel that feeling, allow it to come. What you'll find (with anxiety at least) is that if you don't resist it but regard it with a welcoming curiosity, it will dissipate fairly quickly and leave you with a kind of energised readiness. "Well that was a thing!". If feeling frustrated is a natural response, and you fight with yourself not to feel that, it creates an incredible tension - you push the feelings away and they just push back harder. You kind of learn to let the frustration come feel the feelings in a healthy way.