A hose broke and mixed water in with the oil.
I would recommend having this condition inspected as soon as possible. If your oil and coolant are mixing, severe engine damage can result; coolant can dilute the oil causing it to not lubricate the engine internals. Also, oil does not distribute heat as well as coolant, nor will oil flow through the small passages of the radiator.
Once you have a mechanic diagnose your fluid mixing issue at the source, have the issue repaired first. Once this is done, all cooling system parts that are rubber, as well as the radiator, will likely require replacement in order to function properly. A simple oil change should fix the coolants contamination of the oil.
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