PLEASE HELP! How do I tell my Fiance that I’m Pregnant for my Ex

Hi Daniel!
I am a 23-year-old girl, about to marry a man I truly love. About five years ago, I ended a quite painful relationship, and my husband-to-be helped me to get over it. We started as friends, but gradually fell in love and grew to appreciate one another. Eventually, he proposed to me and I gladly agreed to be his wife.

Our wedding’s due in September. We haven’t had sex so as to consummate our relationship on our first night together. Although neither I nor him are virgins, we agreed to wait until after our marriage.

All was going well, until I ran into my ex about two months ago. Long story short, we met up, had a few drinks and ended up in his apartment. Recently, I found out I’m pregnant. Neither I nor my ex want to continue our affair, and I feel terribly guilty.

The million naira question is: do I tell my fiancee of my one-night stand, or do I seduce him and make it appear the baby is his?

Please, What should i do???