First think practically, decide your goal, then how to attain it. If required, resort to legal proceedings to attain your goal. Simple? Now, your wife has left you voluntarily and she wants to marry another person. That should end any desire for you to get her back or to be depressed. Depression is a sign of weakness. So, overcome that first. The only thing that you should be concerned about is that your previous marriage should not void your future marriage. So, just inform the other side that its OK for her to go and get married but only after voiding the existing marriage in the interest of both parties. Do so only through intermediaries and not in writing. If they are ready. Fine, start legal proceedings mutually to meet that objective. If not, you start legal proceedings unilaterally with that as your ONLY goal.
You should not worry about her marrying another person while she is married to you. Thats not your problem. Thats hers and her husband's. Do not file any petition to restrain her from another marriage. On the other hand, let them get married. Then you can use that to seek divorce. It will be very easy for you.
Do not file any RCR (restoration efforts) with genuine intent to get her back. That would be very stupid of you. Do you really want a woman who is forced to live with you against her wishes? The only reason that you may do so is to show evidence in your divorce petition that you tried to get her back. To that extent, and for that reason only, file one. Of course, in the hearing, you pretend that you really want her back.
Simplify things, shed emotions, think rationally, have a PLAN in place, act accordingly only.
And I cannot leave without giving you the usual advise: ADVOCATES ARE IDIOTS OR CROOKS. SO, BE CAREFUL ABOUT THEM. DO NOT SIGN ANYTHING THEY SHOVE IN FRONT OF YOU AT THE LAST MINUTE. MAKE SURE THAT YOU HAVE AT LEAST A COUPLE OF DAYS TO REVIEW AND UPDATE/DELETE/ADD TO IT. DO NOT DISCUSS YOUR ENTIRE STRATEGY WITH YOUR ADVOCATE. ADVOCATES ARE LIKE PROSTITUTES. THEY WILL SELL WHAT YOU HAVE IN MIND TO THE OTHER PARTY. MOST OF THEM DO THEIR LLB BECAUSE THEY COULD NOT GET INTO ANY OTHER ALTERNATE COLLEGES LIKE MEDICINE, ENGINEERING, ETC. THAT SHOULD TELL YOU ABOUT THEIR IQ.