OP everyone is right when they tell you that this is sexual assault.
But the thing you might find helpful to think about is that these assaults don't happen in a vacuum.
I imagine that there is quite a lot going on in your marriage that you have been trying to rationalise and convince yourself is acceptable.
For example, I'd be astonished if your husband didn't have a strong attachment to porn. If so, I wouldn't be surprised if you told us that you've never had a problem with it and have even defended porn on other threads.
Neither would I be surprised if there has been a context of your husband overriding your wishes and boundaries or that you have become inured to it over the years and have even convinced yourself that this is relatively normal in most marriages.
Sometimes in situations like this something happens that forces women to see that context in a new light. This can range from sexual violence, infidelity, financial secrets or one apparently discrete act that on first discovery, appears to be aberrant and isolated, but on reflection, really isn't.
It can be very uncomfortable too, especially if you've been bargaining away other behaviours and refusing to see the patterns that were forming.
So I'd urge you to reflect for a while and start 'seeing' your husband in a new light. This is quite frightening because it can mean re-evaluating your position and losing defences you've put in place in order to survive as a woman in this marriage. It can leave you very vulnerable when those cleverly crafted defences start to dissolve - and before you create new ones.
Please don't see these assaults as isolated events. That would be a terrible mistake.
Good luck.