You need to do what's called a "mandrel" bend which just means bend it over a curved form so you don't put a corner in it. I get three screwdrivers with round plastic handles (maybe 1 1/4" diameter) and set them up so the bend is centered about 2/3 of the way up from the bottom tip of the spring. Two screwdrivers on one side, one on the other so you are bending across the single one.

Before you start, lay the spring sideways and ink a line showing the starting curve so you can compare it after you bend it. To reduce strength, bend a little more curve into it. To make it stronger, you flatten it some.