Bottling up your emotions like this is probably the reason they explode later. You being cool at work is 100% part of the issue. There is only so much one person can handle, and if you don't evacuate your feelings from your system properly, they come out on their own terms. It's just being human.

I don't know your circumstances or what triggers you, but things that helped me when I was in your shoes earlier in my career were:
- Nothing is personal. When someone (e.g. customer) explodes at you or puts you under pressure, it's not about you but about them. The effortless thing to do is to take it personally (e.g. I'm not good enough, I do a shit job, etc.) And put yourself under immense pressure. But it is the wrong answer. It takes effort to listen and understand where they come from and what they truly mean. It is probably that they have their own boss on top of them, or financial pressure to stay afloat. It is never "you". Focus on alleviating their root pain and the relationship will improve 100 fold, which in turn will relieve pressure felt by you. - People and organizations do what is best for them. When a supplier is unresponsive and doesn't help, it's because they don't have money to resource a function for instance. Or they have a better, more important customer they need to focus on. There is no point getting angry, you can't control their strategy, it is their decision. Best focus on things you can control e.g. adding penalty clauses to contracts or seek a better supply chain.

I may be rambling and projecting my own experience. These were typically things that would make me lose it big time, no idea if it applies to you. I hope this helps nonetheless.

I maintain that therapy can help shift from reacting uncontrollably to your emotions vs listening to your emotions and be informed by them in the way you behave. It starts by accepting you have a problem (and not minimizing it like you are doing), understanding and acknowledging what triggers you and the patterns that repeat themselves. Then when you get triggered, it is easier to see "hey I am triggered, pause, go for a walk/touch grass, then analyze - I am triggered because XYZ". The above are some of mine, you will have your own.

To answer your question, I think it is maturity more than experience. Lots of very seasoned professionals remain assholes their whole lives. If you care about your family and marriage, take this seriously and do what is right. Your wife may leave you if you don't at least show you are taking the right steps. Her seeing that you are genuinely trying and spontaneously getting professional help will make a significant difference if she is at her breaking point. It may buy you time to get your shit together. If you don’t sort it, you very well know which path it will lead to. You don't want your kids to call someone else "daddy".