بسم الله الرحمن الرحيم
The jewelleries which were given to the girl from her parents, they are owned by the girl or her family. Hence in case of separation, the girl may take back those jewelleries. As far the jewellery which you gave to the girl is concerned, if you gave it into her complete possession then now it is not lawful for you to take it back. But if you did not give it into her complete possession then you may take her back. Further, if you have not paid the mahr to the girl, you must pay it. In case of talaq, the maintenance expenses of iddah period shall also be wajib on you. But the demand huge amount in the name of expenses of marriage made by the girl’s side is unlawful and haram categorically. They have no right to make such a demand.
First of all, you should try to settle the matter. From both the sides 2-2 serene and sensible persons should hear both the parities and remove their complaints and ask both of them to live together in peace. Yet, if there is no hope of settlement between you and talaq is inevitable then you should not give three talaqs. It is sever sin to give three talaqs together and sometimes it causes remorse and regret. You should give only one talaq bayin, the nikah shall come to an end after it. Then the woman shall have the right to marry someone else after observing her iddah.
Allah knows Best!
Darul Uloom Deoband