A separation is not always a traumatic experience. Depending on the ill-health of a relationship, it can be a healing time, full of relief and contentment. Regardless of whether it is a painful experience, it does indicate lots of new space in your life, space and time that you previously gave to the dysfunctional relationship.
I believe that exercise is a critical component of recovery. I also believe that you intuitively know what you most need in different stages of your recovery. While a sponsor can often point out patterns or tendencies, it is not their role to design your recovery plan. I have spent a fair amount of time involved with 12-step programs, and your sponsor's insistence that you drop an exercise class to do an additional meeting when you are already attending three meetings a week is (in my opinion) inappropriate and overbearing advice. Many people with strong recoveries attend a single meeting a week; folks who live in isolated circumstances may never attend in-person meetings, but make sober connections via the internet. There is no mandate as to quantity of meeting attendance in AA!
I think it is outrageous that folks are telling you how many meetings you need to attend! Every individual needs a different "recipe" for their sobriety support. You are not a newcomer. You have 19 months, and - hopefully - have done enough internal work that you are learning to trust your instincts.
I hope that you will decide for yourself what you most need. If I were receiving this sort of advice from my sponsor, especially if they were making it a "dire warning" which was designed to frighten me, I would drop them as a sponsor.
I believe that AA is a path to sobriety, but it is only one avenue. Many people build successful sobriety without any AA attendance at all! Exercise is a critical piece of many people's commitment to sobriety (it is for me).
I attend one to two meetings a week. Some weeks - if they are over-full with other healthy sober activities, like kayaking or hiking trips, community volunteerism, or increased responsibilities at work - I might skip meetings altogether. I have many sober relationships in my life as a result of formal meetings, and I connect with those folks by doing other sorts of shared activities with them. Going hiking with a beloved AA friend can generate just as much sobriety support and emotional learning as sitting in a church basement sharing for three minutes with a group of people you may or may not enjoy or respect.
Recovering from a difficult relationship, feeling powerful and beautiful inside your body will offer you confidence, and exercise can generate that particular power. I think you are absolutely on the right track!