As others already pointed out, the nuclear exit strategy was decided upon under Merkel's conservative government.
Some added information so: The Green party pushed for an exit of nuclear power as part of a social-docrat government. This exit eas actually pretty well worked out and planned. When Merkel took, one of the forst things was to throw that rather good plan out. Only to revert that decision, hastly at that, after Fukushima. That second nuclear exit, the one Germany is currrently going through, was hastly done, ill planned and rushed.
And lastly, nuclear power does exactly nothing to compensate for reduced gas deliveries. Germany, as in deed a good portion of Europe, is heating with gas. And not nuclear power or electrical.