Lots of children don't meet the suggested goals on training-readiness checkllists until well into their third year or so. If you've already 'tried everything,' chances are your son feels pushed into something he was not yet prepared to accomplish. Now 'fear' is his excuse, but it might have started out as less-complicated 'resistance.' Now, his fear may actually include a fear of failure or of disappointing you, but he's way too young to sort all that out.
If I were in your position, I would assure my child that he will want to use the potty just as soon as he's ready, and so I'm going to leave that up to him. Mention that all big boys use the potty, and he will know when he's ready, just like he knew he was ready to walk and talk. He just did it!
Meanwhile, Dad could take him on occasional 'wilderness' outings, and casually let him observe Dad peeing on a tree. No pressure, just a happy, satisfied daddy using the Great Outdoors naturally, the way all the wild animals do it. I'll bet that captures your son's imagination, and he'll want to try himself once he realizes there's no requirement that he do so. This has worked for a couple of families I've known with reluctant boys.
And at home, Dad can use floating cereal for target practice. That also makes peeing (at least while standing) fun and non-threatening.
Meanwhile, here's an informative website you might find helpful. It gives a few variations on"readiness" checklists, plus tips on various training strategies, the best ages to start them, and the advantages and disadvantages of each approach: http://www.parentingscience.com/potty-training-tips.html