Forgot to put Anti Freeze in Radiator- possible damage ?

OK , this sounds daft in this weather ( and it is ) but basically ive been topping the expansion bottle in the car about once a month for the last 4 month with about 2 litres of water.So its had roughly 8 litres of water - i presume water is getting either into the engine or a very tiny leak somewhere - i can live with this, its a 2nd car so i aint too fussed.Anyway to cut a long story short ive diluted it that much theres fook all anti freeze in it and now the rad and expansion bottle is frozen solid, i tried starting it the other day but obv it wont turn because of this.All i can do now is wait for a thaw and see what happens, any car experts give advice ? Will i have cracked the engine block or done any other damage by trying to start it ( about 6 times ) the other day ?