I agree with others that U.Mass Amherst is not a safety. It is however very good for CS if you get accepted, and I do believe that you have a decent chance of being accepted.
If you are going to apply anywhere ED, then you need to first make sure that it will be affordable. I would be very, very cautious about taking on more than the federally subsidized amount of loans (which I think might add up to $27,000 over four years) even for Cornell and even for a CS major.
If you do not get need based financial aid, then $80,000 sitting in the bank might cover the first year at Cornell. Where would the other $240,000 come from? Cornell is a great university, but for CS it is not that much better than U.Mass that it would be worth taking on much debt.
In your situation I would be tempted to also apply to U.Mass Lowell. It will be affordable and I think that your chances of getting accepted there are very good. UNH is another possible safety that comes to mind.