Praise be to Allah.
What you have mentioned about adhering to Islam, praying regularly, treating your mother kindly and doing your duties is something that makes us happy, and you deserve to be appreciated and praised for it. What you have to do is to continue to adhere to the path of righteousness and obedience by keeping away from haram (unlawful) wealth and stop thinking about taking a riba-based loan, because riba is a major sin that dooms one to Hell. Allah has warned the one who does that of punishment. People like you should not fall into this major sin that incurs the wrath and anger of Allah. None of the things that you have mentioned could be regarded as a legitimate excuse in sharee‘ah (Islamic law) for you to go ahead and commit this sin. What peace can there be in doing haraam actions? Will you find any peace by living in a house that was built on a foundation of sin? Is there any peace in spoiling the relationship between you and your Lord, may He be glorified and exalted? There can be no doubt that you will never find peace of mind or feel calm if you go ahead and commit the sin of riba, because of the warning that the Lord, may He be exalted, has issued to sinners of what they will experience of distress and a hard life in a spiritual sense. We have discussed the prohibition on buying a house with riba in the answer to question no. 143149
What you have to do is to be patient in putting up with your mother’s attitude and difficult behaviour; treating her kindly is obligatory no matter what she does and no matter how her behaviour and actions upset you. There is no sin worse than kufr (disbelief), yet despite that Allah, may He be exalted, has commanded children to treat their kaafir (non-Muslim) parents kindly and to give them good company. What your mother is doing is something that can be borne with patience; in fact it is possible to put up with that which is many times worse than that. There are people who are less religiously committed and righteous than you who do that.
The solution that we think you should look for, which will keep you further away from this pressure, without falling into error or sin, is to think again about your refusal to get married, because what you mentioned about husbands not agreeing to your helping your mother financially cannot be true with regard to all of them. Rather you may find someone who will join you in helping her. The husband has no right – according to sharee‘ah – to interfere in your financial affairs if you want to help your mother. See the answer to question no. 4037. You can also make it a condition in your marriage contract that you should be able to work in a permissible job and spend on your family, if you want more reassurance.
We hope that marriage will be a solution to your problem with your mother and that you will stop thinking about taking a riba-based loan, and that this will help to reduce the nervous pressure that you are feeling. We hope that Allah, by His grace and bounty, will bless you with marriage to a good and righteous husband who will understand your situation and help you in it. So put your hope in Allah that He will enable you to do that. Do not hesitate to think again about your refusal to get married; perhaps marriage will be the key to the solution for what you are suffering.
We ask Allah to help you to do that which pleases Him, and to help you to treat your mother kindly, and to bless you with a righteous husband and good offspring.
And Allah knows best.