Sorry i missed your dilemma hun!
Here's what i do in exactly your situation. Wear Cossie, wrap towel around myself, walk to pool and take off towel as near to the pool as poss. Some have hangers on the side. Then i get in with the kids, and become SUPERMUM! I have the most fun i possibly can, playing games, playing with floats, diving through legs, handstands, slides etc etc, so, even though i am fat, i am the BEST mummy there! That makes me feel really goooood! xx
Go next week hun, Sam will love you for it!