Imposter syndrome at a funeral!

So my fiancé’s dad passed away in February of this year. I never got a chance to meet him (my fiancé was taken in by family while his dad tried to get his life back on track) . We had the memorial service today because his family is so spread out that the only time everyone would be together was this past week and this coming week for our wedding on Saturday (the 5th) I had to keep myself from crying and I felt an ache in my heart for someone I never met. Sure it felt like I had after hearing all the stories and seeing all the videos/pictures but still. I felt as though I had no right to be crying at this “celebration of life” (family insisted to call it this because it ‘is not a sad thing and they were celebrating who he was as a person”) I just don’t know what to say because I didn’t know him so I don’t know where to go in terms of comforting the family that I am so close to.