I am 59. A widow. If I entered in a domestic partnership can I still receive widow benefits
Yes, as long as your domestic partnership isn't considered as a legal marriage under the laws of your state. And, of course, you'd also need to meet the other requirements for widow's benefits, which can be found in the following section of Social Security's handbook: https://www.ssa.gov/OP_Home/handbook/handbook.04/handbook-0401.html.
You may want to strongly consider using our software to explore and compare your filing options before you file for any benefits.