I have been divorced for about 10 years and we were married for 25 years. He was 59 in Dec 2017 and I am 63. Can I file for Spousal benefits and then leave mine till I turn 70?
No. Unless your ex-spouse is drawing disability benefits, he must be at least age 62 in order for you to potentially qualify for divorced spousal benefits on his record. Furthermore, since you were apparently born after January 1 1954, you will be deemed to also be filing for your own retirement benefits if you file for divorced spousal benefits (https://www.ssa.gov/planners/retire/deemedfaq.html).
You may want to consider using the maximization software available on this website in order to explore your filing options and determine your best strategy.