if i made a egg (pareve) in a meaty microwave may i eat a milky ice cream thereafter?
Yes, there is no obligation to wait after eating food that was cooked in meaty pots or a meaty oven or microwave. In fact, provided the microwave is not a ben-yomo, you could even eat the egg together with ice cream (the combination is not recommended!), even according to the more stringent possition of Remo.
The question of how a microwave oven is defined (for purposes of meaty/milky) is also a discussion among authorities, but there is no need to enter the discussion for purposes of this question.