I was in the same boat as you OP.
My DH watches porn occasionally, he’s no addict and his ‘taste’ in porn is very tame.
I had our twins by emergency c-section, they were two months premature and extremely low birth weight due to blood supply issues from my placentas. DS spent two months in NICU, DD spent four months in NICU.
The day they were born they were taken to a hospital miles away because the hospital they were delivered in were at complete capacity in their neonatal ward. I couldn’t go with them, I was stuck in the hospital with all the other women on the ward who’d had fairly normal successful births and their babies were right beside them.
DH had to go home after two days staying in with me. I was discharged the next day (shouldn’t have been but the midwives knew my desperation - I needed to get to the hospital my babies were staying in) and went straight to my twins, the hospital they were in very graciously gave me one of their rooms for the long term and I spent the better part of two months away from home.
I was terrified every day, DH came when he could (his work were not the most understanding of the situation) and he was terrified too. We experienced it very differently. He had to continue going to work and feared every phone call. I stayed with them and feared every knock on the door to my room.
When DD and DS were transferred back to my local hospital I decided to stay at home and travel to see them every day. When I got home I was gobsmacked. The place was a tip, empty beer cans strewn about the place and when I went on our shared computer to download some of the literature I’d been recommended about caring for preemie babies, autofill in the search bar confirmed that he had been watching porn too. I felt humiliated at the time, like I was the only person going through the terror of two tiny babies in NICU.
I had it out with him there and then, he was ashamed to admit that all he could do was get lost in his old habits because there was misguided comfort there. I didn’t have an issue with just the porn, but the situation as a whole. I got him to tell me his experience of those months I was away, I had been oblivious to how lost he felt, how scared he was that our children weren’t going to pull through. So he just went into automatic mode. He wasn’t proud of it, he apologised. But I gained his perspective on what we were both going through and he gained mine.
From there we both agreed that whilst we were both going through such a traumatic time - our personal experience of that time was very different. I was snappy and nasty a lot of the time because of stress and I vented that at him. I’m not proud of that either.
My DH rarely watches porn and when we do get the time to be intimate he makes every effort to make me know that - whilst he may look at the ladies on screen - I’m the person he’s most into. It took a lot of work to get back to functioning that way though.
Have you been able to talk to your DH about it? I know people might think it’s odd you bringing it up now, but to truly put your mind at rest, maybe just ask him. I can understand why you’re hurt and the low sex drive during/after pregnancy can make what was previously a small issue about porn into a massive one - that’s not including the rest of the situation that had you both under intense pressure.