my prickly pear has been doing great, until this morning I put it outside in direct sun and within a few hours the new baby on the top started to lean. I also watered it the same day. Any ideas as to why? I normally keep it inside in direct sunlight on my window sill. The temp in my apartment is normally around 70 degrees.
Direct sunlight outdoors is not the same as sunlight through a window - UVA gets through glass, but UVB rays do not, so your plant was not ready to cope with suddenly being exposed to full on sunlight. If you want to move a plant outdoors into sun, it has to be done gradually, with limited exposure initially and preferably not in the middle of the day to start with.
Decide whether you want the plant outdoors or inside - if you want it outdoors, just keep it in dappled sunlight or put it in early morning sun, then into shade, increasing its exposure to sunlight over a week or two, until its in full sun all the time.