My sister secretly sells the land plot we jointly purchased

My sister and brother-in-law built their wealth by collaborating with others to invest in real estate when lacking sufficient funds, and subsequently selling at higher prices for profit. Therefore, in 2020, I entrusted them with the funds to co-purchase a plot, recognizing my inability to afford land solely with that amount of money and my desire not to let my savings sit idle. I was also in search of opportunities to earn more than the bank’s interest rates of around 5% at the time.

Two years later, regret crept in as the real estate market dipped and bank interest rates rose. Accepting the fluctuating nature of investment, I had resigned myself to the possibility that real estate might not be my path to wealth and hence did not discuss the matter further with my sister and her husband.

However, when they reached out recently to inquire about my interest in investing in more land plots with them, it came to light that they had sold our jointly purchased plot in 2022, turning a VND13 million profit. My sister explained her lack of communication by saying she thought I had given her the money to invest on my behalf. Acknowledging her wrongdoings, she proposed to repay me VND325 million.

Disturbed by this revelation, I confronted her about her decision to proceed without consulting me, emphasizing that had I been informed about the sale, I would have preferred to reclaim my investment regardless of its profitability.

The situation escalated when my husband, equally upset, expressed his dissatisfaction on social media, which led to my sister and brother-in-law feeling aggrieved. Caught between my husband and them, I was further distressed by their choice to conduct the sale in secrecy, especially considering their substantial wealth of at least VND10 billion compared to the financial sacrifices my husband and I made to contribute the funds, only to be overlooked in this manner.

Our family dynamic had already been complicated by our mother’s passing when I was 15 and my sister’s marriage which limited our interactions. It was only upon marrying my supportive and understanding husband that I felt an improvement in my life, making the betrayal by my sister and her husband even more painful.

I thus declared my decision not to engage in future co-investments with them, treating the VND300 million I had given as a loan to their business. I demanded repayment with interest, choosing a 6% annual rate reflecting the bank interest rates’ fluctuation, and explicitly stated my disinterest in the VND13 million profit from the land sale.

Upon hearing my decision, my brother-in-law displayed annoyance and requested my bank details to return the money, suggesting this repayment would sever our familial relations.

I’ve been contemplating hard since the incident. From an objective viewpoint, am I being too harsh with my sister and brother-in-law?