Paleo's right, they are harmful to your plant. A simple solution of dish soap and water can be applied with a spray bottle, doesn't hurt the plant, kills the aphids. Sometimes you have to reapply a couple times, if you miss a spot or the ants bring new aphids to the party. That plant is doing something strange, any time a plant is week it's like ringing the aphid dinner bell. Tough to say if your plant is just chicking in an odd way or is possibly trying to send out multiple oddball blooms, either way, making sure it gets as much light as possible will also toughen up the skin and make it less appealing to the bugs, this could also encourage healthy growth.
'Pacific Blue Ice' is a favorite of mine, goodluck nursing it back to health.