The ants aren't eating your bell pepper plants. By crawling all over the flowers, they are helping to polinate them, which is a good thing.
As for getting rid of aphids, the stronger your plants are, the more resistant they will be to aphids. Growing your plants in well-mineralized soil gives them all the nutrients they need to produce their own natural "pesticide". Next year, put lots of compost and manure into your soil. But since it's too late for that, you could get some lady bugs to eat the aphids. Yes, you will kill the aphids. But at least you'll be making some lady bugs very happy.
~I am only interested in results. If something works, then an explanation is really just an intellectual exercise. ~