I think the worst came at 32 weeks. This doesn't mean this will happen to you, but... my DD separated my rib from the tissue that connects them all together. I was making the bed, reached up to the corner and felt her kick and then felt what may be described as velcro undoing EXTREMELY painfully!! I screamed, laid down and sobbed. It was sore for weeks.
Eventually there won't be enough room in there for them to hurt you as much. Eventually they will drop and you will breathe again. Eventually you will have two beautiful babies in your arms and you will say "ribs? what ribs?" hang in there!