By Christoph Steitz FRANKFURT (Reuters) – German oil and gas firm Wintershall Dea said on Wednesday it would stop payments to Russia and write off its 1 billion euro ($1.1 billion) financing in the Nord Stream 2 gas pipeline, which was suspended last week. The group, one of the five co-funders of Nord Stream 2, said Russia’s invasion of Ukraine had “shaken the foundations of the company’s work in Russia to the core”. French utility Engie, another backer of the pipeline, said it had a credit risk exposure of up to 987 million euros to Nord Stream. The remaining financiers of the Gazprom-led pip…