2-3 x/week for 30 mins should be a good start. This is VERY important as we women age. Muscle mass drops at a faster rate after the age of 50. Cardio is great, but ST or RT will keep you strong. VERY important!
Important is a relative question, Mom. Obviously, nobody went to gyms or did this kind of exercise for most of human history, and the people who have been studied in those clusters where they live the longest healthiest and least obese lives don't do any kind of formal exercise for the most part. What they do is eat well and don't live sedentary lives. That being said, you love to work out, and for weight loss resistance training might be even better than cardio. It tones your body, so you have a better shape. It offers a variation in your workouts so you don't have as great a risk of suffering repetitive workouts as those who, say, run every day. If you have a meditative soul, it's much better than taking classes to go to the gym and just lose yourself in your breathing, as proper breathing is really important for proper weight lifting. So for anyone who really loves formal exercise, weight training varies the routine, builds muscle that supports all the things you do, tones the body to a better shape, might be better for losing weight, and allows a focused concentration that can be really nice. It can also be dangerous if you do things you've never done before and do them wrong, and knowing how to do them right is very hard because everyone has a different theory. So there's that. No serious athlete skips weight training, not even today's golfers. It also helps shirts to fit better.