Need advice

Ok so me and my fiancé have been together for 18 months living together, we got engaged in March and he had asked if we could start ttc. I suffer with severe anxiety and also depression.

Let me start by saying other than this issue we have a good relationship.

We have many times discussed porn and both agreed we don’t want it in our relationship I feel like it’s cheating and he agreed. I have several times found on his computer and phone that he had been going on porn sites and I questioned him and he denies it so I let it go (but deep down inside I can’t fully get over it and always feel like he may be up to something). So a few months ago I had a look on his phone and he had been going on YouTube and watching porn again I was very upset felt not good enough and questioned him and again he denied it. It’s been a couple of months and I still occasionally check his phone for peace of mind. Well with my anxiety I don’t really leave the house much but I’ve recently started learning how to drive to help with the anxiety etc. Very often when I’m back from my driving lesson i find the YouTube history has gone surprisingly. This week after my driving lesson I had a quick look but everything seemed fine but something was telling me to look again, so I decided to go onto his Facebook and when I clicked on his search bar there is a search on the day of my driving lesson with milfs and bang tidy.

I have not yet told him what I have seen since I wanted advice.

Please help, I love him dearly.

Thanks