On the one hand, you have the issue that as a human being, even fairly average sexual drives and habits are seen as something despicable to be ashamed of and lied about, judged as horrific even by one's own partner, however much they think or say the wouldn't be judgmental, they would not look at you the same again. This is definitely not unique to men, or women.
On the other hand, you have this lying to cover up the shame of it, and it's bad for a person's soul, psyche and marriage to be doing things in an unwholesome and dishonest way.
One thing that occurs to me - a person who for whatever reason is not getting sex, well even if it's a condition they may still have sexual urges on some level, and if they cannot satisfy those urges without... doing something they cannot do... without the negative feelings, pressure, guilt, perhaps almost existential feelings of inadequacy and worthlessness coming to the fore, they are still going to have those urges, still going to feel a need to deal with them, perhaps somewhere safe, away from bad feeling and disappointment, and being asked if they are gay.
It seems like there is a middle ground somewhere, to be honest. It is surely easy to understand the concept of someone lying if what they feel is something sickening to be ashamed of, and it is for sure easy to understand how you feel, being outright lied to and confronted with something so tawdry, but you know... from what you've said, it doesn't sound like there is some great deficiency of love between you, or some huge wish to hurt anyone.
What do I know, I guess.