I may not have the definitive answer but you may want to try the following. In a swimming pool try swimming around using a snorkel, nose clip and swimming goggles. This should get you used to water around the nose and eyes. Once you get comfortable with this try removing the nose clip (still wearing the goggles and breathing through the snorkel). Once you’ve got used to breathing in and out through the snorkel try removing the goggles ans breathing through the snorkel. In the end it is a case of one step at a time until you are comfortable breathing without goggles/ mask. At the start you may want to do all the above holding onto the side of the pool and then progressing to swimming around.
Hope these suggestions help