Hi I don't think that close to a North facing window would be too much light, it's probably not enough light. I keep mine outside hanging in a tree in the summer, and they are getting full sunlight in the morning and the afternoon, bright filtered light in the middle of the day. I suspect that it probably is getting too much water, and definitely not enough light. Dark green is a signal that it wants more light, and drooping suggests root loss. You should probably check the condition of the roots. Black or squishy (technical term) could mean that it needs a repot, the bad roots cut, and some peroxide to clean the remaining roots up. If you are going to give it more light, wean it gradually to more light to prevent leaf burn.
Whew, all that aside, if you could provide a pic, it definitely would tell more about the condition. It could very well prove me wrong.
Hope that helps.