She has had pain in the past, that was a lot of what we worked through in therapy. I was doing the typical man thing of minimal foreplay and we hadn't been communicating well with each others preferences. We've made big improvements in that, but there's almost a barrier to foreplay now. I obviously don't know for sure that she enjoys the sex we have, but she does climax most times. It's possible she could be faking that, but it'd be impressive as she has leg tremors and kind of seizes up.

Thanks for your help. I agree with what people are saying, it is a form of cheating which is why I need to stop it. I have considered speaking to her about it, but I want to ensure the habit is well and truly buried before I do. I commented on another user who was telling me I need to tell her right away - that would be suicide.