Have you married second time only 90 days after obtaining the ex-parte divorce decree? If Yes, then, you need not worry.
Has your first husband received the court notice in ex-parte divorce case? If yes, then you need not worry.
Shall you withdraw all your cases? What are all those cases? By your statement, I see only two cases, one is S.125 case and another one is divorce case.
The question of withdrawing divorce case does not arise, because you alredy got ex-parte decree and lateron you got married.
In case of Sec.125 case, you have to withdraw the case as you are remarried. As this case also decided ex-parte, there will be technical problem of withdrawing the already decided case. But you can move an application in the court saying that you remarried again and hence the maintenance order passed in favour of you be made ineffective. The court will pass the order in such manner.
Now the problem with your first husband: You must be strong enough to deal with him. You should tell him shut up and get out or you will get him arrested under Section 354, 506 and 509 of IPC for outraging the modesty of woman and insulting you. Forget about past relation with him. He is as stranger as any one of us here. Once you got divorce decree, he has no business to talk, approach or put any demand to you, more particularly the demand of physical intimacy. If he does so against your will, he is liable to rape charges. If he utters foul language or indecent behaviour, you have got remedy in criminal law. Through your advocate you tell him all those things. Even then he harasses you, you have option of approaching police and criminal courts against him. If he harasses you on telephone or comes at and near your residential accommodation or your place of work, you can take protection orders against him under DOMESTIC VIOLENCE ACT. Once, I say this, some of the self proclaimed legal pundits come to catch my neck saying that how a case under Domestic Violence Act lies against the husband of first marriage? Let them talk as they like, but a case under Domestic Violence Act lies against the first husband, if he harasses you to meet his unlawful demands.
Wish you get strength to come out of this troubled situation and lead a happy and peaceful life.