I have a 1991 buick regal and while I'm driving the car just cuts off where ever I am and I have to let the car sit awhile before I can start it again and under the hood I smell burning oil but I have to keep putting water in the radiator I took it to the shop and they said my head gaskets are going out I checked my oil and water is now getting in the oil they told me to get some sealant for the head gaskets and pour it in the radiator and it should help temporarily.I don't drive it to far or too much anymore what can I do to fix this problem until I can get the head gaskets fixed properly? And how can I get the water out of my oil until I can get it fixed?

Unfortunately, there's nothing you can really do. My advice is to stay away from sealer products--they can have unintended consequences that cause big problems later.

Getting the water out of the oil can only be accomplished by changing the oil.
But, you need to stop the water from getting in there or you'll have to repeat the oil changes until you do.
Stop-leak products have not always been successful at fixing head gasket failure and often give a false sense of security.
Without knowing the overall condition of your car I can only state that you may well use the money that you would spend fixing this car as a down payment on something newer and more reliable.
Only you can make that decision.