How do I know this?

So I haven't written for a while because well I haven't known really what to say. As I was thinking about what I could say, I thought of an experience my companion and I had a couple weeks ago. We were teaching a family about the plan of salvation and how it helps us know where we came from, why we are here on earth and where we go after this life. The Dad who is catholic, asked me how it was that I know that there is life after death and that I will live with my family forever, even after we die. In this moment I really thought about what he said, and a rush of emotions came over me.  I just told him from all of my heart that after my grandma past away almost 3 years ago, I was really sad, and as I prayed to my Heavenly Father to recieve comfort, I felt a peace like I hadn't felt before. I knew that she was with him and with my grandpa again. I knew that because they had been sealed as a family in a Temple of the Lord by his authority and also my parents with my siblings and I had been sealed, that I would see them again, that we would be an eternal family. I know that death is not the end, I know families are forever, I know Christ lives and so will all of us, and that if we follow his commandments and teachings that we will all live in a state of endless true happiness. I know this is true through prayer, through studying the scriptures, the spirit has told me through an undeniable feeling in my heart and soul that this is the truth and the only true way to God. I want to invite all of you also to really think about this, to pray and ask Heavenly Father what is the truth and as you read in the Book of Mormon and come to our church services that you will feel as I did the undeniable truth of the Gospel of Jesus Christ restored.