Need advice for relationship with older partner

Hi,
I am new here but have been viewing the forum for a while. I would really like some advice on what to do next.
I have been with my partner for a year, he is 46 and I am 28. I came out of an 8 year relationship prior to meeting my current partner, so the whole experience is relatively new to me.
We have enjoyed some absolutely mind blowing sex sessions however my partner has never been able to orgasm through intercourse and normally relies on himself or me "finishing him off" with a hand job. At first he blamed this on confidence. About 4 months ago he also broke it to me that he was using Viagra. I did feel a bit betrayed but understand his reasons for not telling me initially and that it must have been a difficult subject for him to talk about. Even using Viagra he cannot come through intercourse.

All these things have completely cracked my confidence, to the point where I am now nervous about having sex with him and have ended up in tears during or afterwards - obviously this has knocked his confidence too and it is a bit of a vicious circle.
I have 2 children and was very nervous about having sex with a new partner - and this really hasn't helped. My partner said he was nervous about how I would feel when we first had sex but I feel fine. However I cannot help but feel this is all my fault and maybe I am not tight enough, maybe I don't feel right - so many things going round my head. I have been concentrating on doing my pelvic floor exercises but have no idea if this is making a difference!

I have asked my partner what is wrong & he gets frustrated as I ask the same questions over and over - I am convinced it is me and he doesn't want to hurt me. He said he has had the issue in previous relationships and found it difficult to maintain an erection with his ex once he knew she had cheated on him. Then he says it is his age, his shifts (he does work long exhausting hours), his confidence etc - but I really feel like we've gone through every possible excuse and nothing is improving.

I have been researching the issue and know he looks at porn - which he states is no more than twice a week but I doubt this. He has encouraged us watching it together, something I haven't done before but I explored with him recently to see his reactions.

What also gets to me is he manages to toss himself off when I am not around and then can't get it up for me. I mentioned I had looked at this site and maybe he try it - but he kind of knocked it on the head and said he would be too angry not tossing it off for a week! He doesn't see it as an issue and is starting to get annoyed with me mentioning it.

However I see it as a big issue and increasing, and obviously it is increasing the pressure on us both each time we have intercourse.

Any advice please? I just want to cry. I love him to bits and never imagined I would be in this situation - and I still really believe it may be me that is the issue.