XP: milk out all night

RockyRoad3

Last night I defrosted 3oz of frozen milk. Aria didn't end up eating any of the bottle.  I left the bottle out thinking she'd be awake again in a couple hours and I would give it to her then.  She ended up sleeping through the night so the bottle was out about for about six hours and then I put it in the fridge.  I know all the rules about breast milk, but what would really happen if I gave it to her?  It doesn't smell sour.  Would it be really horrible?  It makes me want to cry just thinking about pouring it down the sink.