AnotherStander has given you some fantastic advise. To respond to a couple points:
Originally Posted by "Dan"
If I had been in a relationship with someone for 8 years.. and the person I was with cheated on me - let's say a physical affair lasting 1 year
I'd be 100% done, no question. You watched porn and messaged women, very different.
Originally Posted by "Dan"
As an anniversary present, I made my W a little gift - a short stop-motion film
My ex-wife did something similar--she sent me a Photo DVD of all the good years we were together. I watched 1-2 slides, vented to friends she wouldn't leave me alone, and never replied.
Originally Posted by "Dan"
I do see how you would feel it’ll make things harder to deal with.
Yikes! She tells you it makes this harder for her--and you disagree?!
Originally Posted by "AnotherStander"
I just thought it was a nice gesture, but I can see why it affected you negatively. I will keep that in mind in the future.
Masterful response--1-2 lines explaining why you did it, validating her feelings, and not apologizing.