I think there is no way to really know how you will be until you are there.
I read a poem I wrote at my youngest child's funeral. It was hard, but surprisingly I didn't cry. It may be because I wrote it, so the emotion was felt through my words, rather than having to 'feel' them.
I read at my brother's funeral last year (again I wrote a poem for him), others cried at it (one because her mum had recently died and it brought up memories).
My dad was supposed to conduct my brother's funeral. He'd seen me for my child, so was sure he could do it for his. He's a very strong man, so we thought he'd be fine. He fell to pieces, really fell to pieces. It was left to my mum - unprepared, to take over and read for him.
So you may well be surprised at your strength. Tears are fine. They're just salty drops of love. Whether you cry or not, your mum will be so proud of you.
I am so sorry for your loss 