First off, don't measure the amount of video memory used by the image by the disk size of the file. There's a similar question here which covers the topic and I've linked to a very good answer that will cover most ground on how you should measure VRAM usage accurately. As a quick guideline though, it depends on the size and amount of colours in the image and how the image is saved and packed.
With this in mind, the image might be a lot smaller than you anticipated or bigger - it would be up to you to check this out. At any rate however, as long as you're not loading a bunch of those textures into memory you would probably be okay but it's a game specific thing. With todays video cards having 1GB + of VRAM, it's trivial to load a few of those textures into memory if that's what you need. It also depends on your target audience and what kind of hardware you expect them to run this on.
So in short: Run with it if you think you need; optimize it later if you need.