All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
First of all, we ask Allaah to facilitate your matter and make a way out for you and bless you with righteous children from your husband, by whom your eyes would be comforted.
We advise you to supplicate as much as possible and seek forgiveness from Allaah and take the permissible means by consulting the specialist doctors and so forth. The matter of having children is in the Hands of Allaah; Allaah Says (what means): {To Allaah belongs the dominion of the heavens and the earth; He creates what He wills. He gives to whom He wills female [children] and He gives to whom He wills males. Or He makes them [both] males and females, and He renders whom He wills barren. Indeed, He is Knowing and Competent.}[Quran 42:49-50] Indeed, Allaah may facilitate for you having children and the problem will be solved.
As regards your husband assuming that you should bear the biggest responsibility for looking for a (second) wife for him, then this is not permissible because you are not religiously required to do so. Moreover, he should not ask you for this if he knows that asking you for this embarrasses you. In any case, if it is predestined that your husband marries a second wife, then you should ask Allaah to help you to be patient and you should take it easy because polygyny is a matter that is legislated by Allaah for great benefits, among which is the need of many Muslim sisters to have a husband, and the need of the nation in multiplying the progeny and so forth.
For more benefit over feeling jealous against a husband marrying a second wife and how to treat this and be patient, please refer to Fataawa 101116 and 91150.
Concerning travelling without a Mahram, this is not permissible as we clarified in Fatwa 83403. It is not enough for the permissibility of travelling without a Mahram that a husband sees off his wife at the airport and one of her relatives receives her at the airport in her country.
Moreover, how would you know that your being between the members of your family will be a reason for lessening your pain; rather, the matter may be totally the contrary. Therefore, we advise you to busy yourself during those days with what is permissible, in addition to keeping company and contact with some pious women as your presence with them may entertain you somehow.