It is depends on the husband if he challenges in Indian court, the decree of divorce taken by you in USA on the basis of section 13 of the Civil Procedure Act & well laid down principle of the Apex & other High Courts of India with regard to foreign court judgements/order/decrees.
If your husband never objected to the US court jurisdiction to adjudicate the matrimonial dispute between both of you as you both were Indian citizens , married according to Hindu form of Marriage under the Hindu Marriage Act,1955, according to which only the Indian courts have jurisdiction to adjudicate any matter under this Act, in such case on the basis of his agreeing to the jurisdiction of US court you get benefit in Indian court.
Another important issue is merits of the case or the grounds on the basis of which the decree of divorce passed. In most of US court divorces the ground is "irretrievably broken matrimonial home".
This ground is not provide under the H M.Act., the law say that the ground under which divorce was granted by a foreign court should be one which is available under the H.M.Act,1955. The Supreme Court of India has held in its landmark judgement in Y. Narasimha Rao case, concerning US court divorce that was granted on the ground of "irretrievably broken matrimonial home" is not available under the H.M. Act,1955 & hence such divorce will not be valid according to the Indian Law hence it shall be considered void divorce in India.
Ignore the summon of RCR suit as filed in India, you need not contest the suit for RCR.A decree of restitution of conjugal rights implies that the guilty party is ordered to live with the aggrieved party. Restitution of conjugal rights is the only remedy which could be used by the deserted spouse against the other. A husband or wife can file a petition for restoration of their rights to cohabit with the other spouse. But the execution of the decree of restitution of conjugal rights is very difficult. The court though is competent to pass a decree of restitution of conjugal rights, but it is powerless to have its specific performance by any law. The non-compliance of the issued decree results to constructive destruction on the part of the erring spouse.Execution RCR decree is not possible in USA.