Carrying Hidden Guilt - A Young Muslim Woman Seeking Guidance

As-salaamu alaykum. I’m a young Muslim woman carrying a lot of guilt, shame, and confusion in my heart. I committed zina with my then-boyfriend, and even though I’ve not always been very close to my religion, I do believe in Allah and I understand how serious this sin is. Before meeting him I had never dated or been involved in anything like that - I was innocent and kept firm boundaries. When we met, intimacy became very important to him, and out of love and fear of losing him I slowly gave in to things that went against my values. It began with messages, then meetings, and continued from there. It’s been two years and everything has been kept secret. The guilt never leaves me, especially when I think of Allah and my father, and it weighs heavily on my heart. We plan to marry in the future, but financial difficulties and complicated circumstances on his side are delaying it. Sometimes I worry about how he truly sees me now; he reassures me, but that isn’t the main thing on my mind. I also wonder whether this will affect our marriage or how he might treat me afterwards. I love him deeply and I’m emotionally attached, yet I live with constant inner conflict, regret, and fear. He thinks marriage will change everything, but at times I worry if that would be hypocritical. I’m not looking for judgement - I’m asking for sincere advice and guidance from people who understand faith, love, guilt, and emotional attachment. TL;DR: I fell into zina out of love, I’m living with secret guilt, worried about my faith and honesty, and seeking sincere guidance. JazakAllah khair for any heartfelt advice.