In a long term relationship and cheating with married man

I'm in a ltr, 15 yrs not married. I met a married man at work, he's a customer and I have been there for 2 yrs. We would flirt back and forth then one day this past summer he kissed me. Weak in the knees kinda kiss. From then on we started hooking up. I'm in my 40's he's older then me but that doesn't bother me. He is married over 25 yrs, never elaborated on his relationship much and I don't on mine. He is always complimenting me during sex which is fine, just not use to it. Tells me he adores me, how beautiful I am, I am a good person, said he has a crush on me, and so on. The other day he said something out of the blue that raises some red flags for me, my one friend that knows about him thinks he is falling for me. Maybe I'm in denial because I don't want to get hurt but the last time we hooked up he said I deserve better than him as he was complementing me during sex. Then he says you make an old man like me very happy. Is this a guilty feeling, trying to end it, or is he falling for me?

I don't want either one of us to get hurt, I thought it was a fling but it really feels like more is coming of this then I thought. I know both of us are doing wrong with lies and deceit, I know I can ask him but I'm trying not to complicate a already complicated situation.