How do I cope with being blamed when things break but ignored when they work?

You built the plumbing the whole company runs on, and your reward is silence when it works and blame when it breaks. That is a punishing bargain, and it wears on you precisely because you do the job so well that no one notices it being done. The better you are, the more invisible you become. But the silence is not the truth about your value. It is the shape of foundational work. No one praises the ground for holding still, until it does not. Your worth is not measured by how loudly you are thanked. It is measured by how much stops working the day you step away. That is a great deal. Since the world will not narrate your value, do it yourself. Quietly keep a record of what you prevented, what you built, what would fail without you. Let your own eyes rest on it. Trade honest recognition with the few who understand the craft. The applause may never come. The importance is real, and you are allowed to know it even when others do not.