Can i file 498a after my divorce petition?

Your advocate is right you cannot file 498a as your divorce case is pending in the court since one year , once you have decided to get rid from him then no use to file false case against him , which will also disturb your life also , get rid from him and restart your life ,

What is the status of rcr and divorce case...in such disputes multiple other cases are filed like cruelty, domestic violence, maintenance etc. Providing evidence is up to you. They take a long time. You can still always file cases. Cases of cruelty or domestic violence etc. preferably must be registered in reasonable time. You will be questioned in them about delay, also have to go through cross etc. and your evidences evaluated. You can file cases but not in a confused state. You must know whether it will benefit you. Your lawyer may be saying it to avoid unnecessary litigation for your benefit or for the reason that he gets nothing in it (in 498a....the government counsel runs your case free). 498a is a way to harass or teach lesson to husband. If that is what you want then go ahead.

Its not that you cannot file the 498-A case now however, if you file it at such a belated stage, it will be a very weak case even if registered and will be considered as afterthought & filed with the only motive to harrass the husband and his family. So, though the reasoning given by your lawyer is erronous, the conclusion that it should not be filed is not incorrect as ultimately such a filing will not be of  help to you.

Since you have filed divorce on the ground of cruelty, you can always file 498A on same set of facts. It will not be considered as an afterthought. 

You can harass your husband and his family to the max by filing multiple cases against them, but at the end of the day you will not get any benefit out of it. 

Contest the divorce case on merits and be determined to not come under any pressure. Sooner or later he will agree for an amicable solution.