The letter group "ei" gets various pronunciations, depending on whether it is in an accented syllable, what letters follow it, and what part of Ireland the speaker is from. Often it has an (e) sound, as in "creidim", I believe.
With a síneadh fada (SHEEN-uh) over the "e", the sound is usually (ay*), as in "féin", self, or "Éire" (AY*-re), but sometimes the pronunciation is (eye), as in "éirigh" (EYE-ree), rise. This word is pronounced (AY*-ree) in parts of Ireland.
"Ei" before "bh", "dh", "gh" or "mh" in an accented syllable may be (eye), as in:
Eibhlín (EYE-leen), Eileen
eidhneán (EYE-naw*n), ivy
leigheas (LEYE-uhs), cure; resembling (leyes) in parts of Ireland
deimhin (DEYE-in), certain
In parts of Ireland, "eibh" and "eimh" in these words may be (ev):
Eibhlín (EV-e-leen), Evelyn
deimhin (DEV-in), certain
The word "geimhreadh", meaning "winter", may be pronounced (GEE-ruh), (GEYE-ruh), or (GEV-roo), depending on the speaker's origin. This may sound confusing, but we have parallels in the United States, where "right" may be (reyet), (raht), (rat), or even (royt). And of course "either" can be (EE-thur) or (EYE-thur).
We will continue to give you one pronunciation, but we will add occasional explanation of variations.