What are 3 examples (with quotes) that show how Shylock's decision to prioritize revenge ended up hurting him?

Shylock's thirst for revenge comes back to haunt him in three ways. First, he is unable to collect the interest that would have been due him on the loans Antonio takes. Next, he loses his quest to get a pound of Antonio's flesh and is almost sentenced to death himself. Finally, he is forced to give up his wealth to be managed by Antonio and left to Shylock's daughter and her Christian husband upon his death. If Shylock had not attempted to get revenge on Antonio, these things would not have come to pass. Instead, Shylock would still be Jewish and have access to his own money as well as more money from Antonio himself.
When Shylock decides to offer the loan with no interest and instead collect a pound of Antonio's flesh if the payments aren't made, he is on a path to cheat himself out of 3000 ducats. Later, he is offered 6000 ducats if he'll let Antonio pay money instead of paying with his flesh. Shylock refuses. He says:

If every ducat in six thousand ducatsWere in six parts, and every part a ducat, I would not draw them. I would have my bond. 

He's showing that he's more interested in revenge than money. Ultimately, this desire to cling to revenge means that Shylock gets nothing other than forced conversion and reduced assets. He leaves the court with less money and no flesh.
Shylock is encouraged when Portia says he can cut the flesh from Antonio in accordance with the agreement. He says, "Most learned judge, a sentence!" when told that he can have his flesh. However, Portia then explains that he cannot draw blood, cut less flesh than a pound, or cut more than a pound. If he does, it's attempted murder and Shylock himself will be put to death.
At this point, he agrees to take the principle owed to him and go. However, Portia points out that he refused the money and wanted the flesh -- so now that's the only thing he can have. She also tells him that he'll now have to be put to death for attempting to kill a Venetian citizen, saying: 

Tarry, Jew.
The law hath yet another hold on you.
It is enacted in the laws of Venice,
If it be proved against an alien
That by direct or indirect attempts
He seek the life of any citizen,
The party 'gainst the which he doth contrive
Shall seize one half his goods. The other half
Comes to the privy coffer of the state,
And the offender’s life lies in the mercy
Of the Duke only 'gainst all other voice.
In which predicament I say thou stand’st,
For it appears by manifest proceeding
That indirectly—and directly too—
Thou hast contrived against the very life
Of the defendant, and thou hast incurred
The danger formerly by me rehearsed.
Down, therefore, and beg mercy of the Duke.

The Duke pardons Shylock but decides that all his property will be forfeit. Shylock says they may as well kill him if they take his money. Antonio begs the Duke to reconsider, saying:

So please my lord the duke and all the court,
To quit the fine for one half of his goods
I am content, so he will let me have
The other half in use to render it
Upon his death unto the gentleman
That lately stole his daughter.
Two things provided more: that for this favor
He presently become a Christian;
The other, that he do record a gift
Here in the court, of all he dies possessed,
Unto his son Lorenzo and his daughter.

He means that not only will Shylock have to convert to Christianity, but he'll also have to let Antonio manage his money. He also has to leave his fortune to his daughter and the Christian she married. Shylock says, "I am content" when asked if he will abide by what Antonio requested. If he said otherwise, he could have been hanged or lost more money. He's so upset by this turn of events that he says:


I pray you, give me leave to go from hence.
I am not well. Send the deed after me,
And I will sign it.



Shylock made his own misery when he chose revenge over simply not trying to punish Antonio with the awful terms of his loan.