You can file a civil recovery suit against her ,if you have transaction account details of bank statements reflect that you have paid an amount to her and she has not returned to you till date. Also in the suit kindly mention about the relationship that you had since after getting court notice of the suit she might file a police complaint but if you already write that you had a relationship with her you will be at a safer side. But before filing a suit, you can send a Legal Notice demanding the amount of money taken by her alongwith interest. Find good lawyer with great civil law knowledge.

Forget her and move on in life 

2) you would not be able to recover money spent on her 

3) in fact she would then file false case of rape against you under section 376 of IPC 

4) if false rape case is filed apply for and obtain Anticipatory bail from sessions court 

though your relationship with the girl was a bilateral agreement, yet, if she makes any complaint in the police you will found yourself in grave crisis,

you may be charged with rape on the false promise of marriage, sexual harassment, beatings, threats, blackmailing, sexual video, etc

Either forget the money or make a police complaint against her, taking your family n trust, for blackmailing, extortion of money, mental harassment, etc. but be ready for the counter attack

-  Supreme court declared that , when  a man and a woman in love live together , is part of the right to life and not a criminal offence, and further live-in relationships is legal in India.

- Since, the said girl is black mailing you in the garb of relationship, hence her such act is against the law as blackmailing is a crime in India .

- You should lodge a complaint/information with police for your safety against her for extortion under section 384 of IPC, and for threatening to implicate in false cases.

- If, police not registered your complaint , then you should approach the higher official of police department , and you can also file a complaint in the court as well.

 - Further , for your safety , you can mention in   your complaint , that she has taken amount from you , and when you asking to refund the same amount from her , she is threatening for implicating in false cases of rape etc. 

- Start with the sending a demand notice for recovery the amount from her.

In the absence of any evidence for having lent the amount or any loan agreement or promissory note or any bank statement to support your claim you may not be able to recover the money given to her.

Moreover if the transaction dates back to three years prior to the date of demand made, it will be barred by limitation.

Hence first you issue a legal notice demanding the money you have give it to her  mentioning the date, time and amount of the different transactions during which the money was given to her, let she acknowledge the loan or receipt and not comply with the demand made, you can file a money recovery suit after that. 

This legal notice may create an adverse impact too  i.e., in retaliation she may even lodge a criminal complaint against you for rape and cheating after having sex with her and refusing to marry her, in that case the police may register a criminal case against you under section 376 and 417 IPC, hence you may have to exercise caution over this aspect too.

1. If you have enough evidence that the relationship with her was mutual and sex was consensual and if she is blackmailing you, then you can lodge a Police Complaint against her.

2. Similarly if there is record of evidence to prove your point of her taking your money, then send a legal notice for recovery of your amount.

1. Do not get sacred much as long as you become pro active to take recourse to law first.

2. So visit the police station fast and lodge a complaint of cheating.

3. The proof you have on payments is clear to nail her down with the case of cheating.

4. Thereafter her case for rape would not stand at all.

5. Do not let this type of cheats go scot free.

Contents of your post suggest the character of the lady.

Ignore the relationship and move on.

The chances of recovery of money from her are bleak, you have no reason to substantiate your case.

Further, if you want to fight, use the proofs you have and lodge complaint before police. 

If she files rape case against you, you can contest the same showing that it  was consented not forced.

She has to prove her case.

Better option is forgive and forget the case and move on.

See if money was lent as a loan then only you can recover same. You can send a legal notice and file suit if she fail to return amount on the notice. 

Though if you spent money by your will you cannot recover same in that case it is better to leave her and amount and move ahead.

You need to file cheating complaint against her and pursue the same in court

1. You cannot recover from her the money that you gave her willingly and without fastening any liability to repay the same with or without interest.

2. So far as her threats are concerned, you should immediately send a complaint in writing to the jurisdictional police station to intimate them about her threats to implicate you in false cases. If and when a FIR gets lodged against you under Section 376 IPC then immediately file for anticipatory bail.

See if you have not taken any promissory notes signed from her in past at time of giving money  to her, so now you can't claim it legally she may also defend legally here you can ask money from her politely or you can forget past amount whatsoever you have given.

Yes, you can be safe by making complaint against her for asking money or demanding money from you for false story of rape case. before she goes in the police station you can go and take prevention action against her for demanding money from you.

1. You should record the calls in which she ask you to give money and threatens you for false cases. 

2. Then you can either lodge FIR against her for extortion by threatening for false cases or you should Send her legal notice for recovery of money but legal notice for recovery of money can have adverse effect if you don't have proof of payments to her. 

3. If you have proof that she have been threatening you for false case of rape after having consensual sex then you should go to police and Lodge complaint against her.

Lodge a criminal complaint against her before a magistrate. State all the facts and circumstances of the case. How she is blackmailing you. The court will summon her and her boyfriends and will do the needful.

1. You have not given her the said amount of money as loan but as gift only for which it will be difficult for you to reclaim the said amount.

2. Having consensual s*x   is not a crime for which she also will not be able to take any action against you legally.