The idea that the Prophet (S) passed away in the lap of A'ishah is found in some Sunni texts and is generally not shared by Shi'is. Other texts say that he called Imam 'Ali (A) to him before he passed away, and this view is generally the one adopted by Shi'is. Here is a Shi'i view on his last moments: https://www.al-islam.org/life-muhammad-prophet-sayyid-saeed-akhtar-rizvi/death-and-burial 

In any case, it wouldn't have been fair for the Prophet (S) to favour A'ishah above his other wives at that time.

That being said, I don't think there is a lot of benefit in speculating over how much he did or did not love her, at the end of the day they were married and the Prophet (S) had a noble and generous personality and extended love to many people, this was part of what made him special and beloved in turn.

I am not sure if it is possible for anyone to offer a conclusive viewpoint on the spiritual impact of using credit cards, since credit cards are quite new and are part of the institutional structure, as opposed to collecting interest from someone vulnerable in a person-to-person transaction.

However, at the least, having credit card debt causes a lot of stress, and having a credit card can also encourage overconsumption and spending beyond one's means, so it is good to be cautious of these things unless it is an emergency or there is no other option. No one ever not-regrets having to pay interest on a credit card.

As for interest in general, the Qur'an is quite clear about its impact. For instance: "Those who devour usury shall not rise except as one rises who is felled by the touch of Satan. That is because they say, 'Buying and selling are simply like usury,' though God has permitted buying and selling and forbidden usury. One who, after receiving counsel from his Lord, desists shall have what is past and his affair goes to God. And as for those who go back, they are the inhabitants of the Fire, abiding therein. God blights usury and causes acts of charity to grow...."(2:275-6)

In addition, it is related that Imam Ali (A) said: “The Holy Prophet (S) has cursed one who accepts interest, one who pays interest, one who buys interest, one who sells interest, one who writes the contract of interest and one who is the witness of this transaction.”

It sounds like this person is going through a tough time.

Life has easy and difficult times, sometimes very difficult times. It is good to have faith that there is light at the end of the tunnel and to contemplate on the verses of the Qur'an about Allah's mercy. Nothing stays the same forever and things often change in ways we could never imagine. Until then, however, it is sometimes necessary to walk in the darkness until reaching the light. The good thing about darkness, however, is sometimes it makes the light clearer. 

Existence is not a choice, since a person who dies continues to exist. However, it is good to have faith that Allah has a plan and does not create anything in vain; just because we do not understand why we, individually, were created does not mean that we do not have our own specific reason for being.

Some might argue that Qur'an 7:172 which speaks of human beings testifying to the existence and lordship of Allah (in the realm of pre-existence, or in some other way) implies that we gave a sort of agreement to existing, even if we do not remember it now. Some might also argue that Qur'an 33:72 implies a sort of willingness to exist and accept the risks/consequences of free will, even if we currently do not want it - God knows best. 

If this person is also dealing with depression or a psychological condition (either as a condition by itself or as a response to challenging circumstances), they could also look into psychological/psychiatric interventions and see if they are useful and appropriate at the moment to help get more zest for life. 

If it is more of a spiritual or existential crisis (and all of the above can go hand in hand), more study and reflection of the Qur'an and theology and the big questions of life may help. In the end, while Muslims, like others, offer answers to questions such as "why do we exist?", it is one of those big questions that people have pondered for millenia, and although religions can provide answers, I think it is also something people often need to find answers for inside themselves.