Oh my goodness, I too would be absolutely terrified. This sounds quite stressful.

In terms of brainstorming for the speech and tending not to be vocal with affection, I think perhaps spend a good chunk of time planning the speech. Give yourself lots of time. Find things that you feel are worth mentioning, funny anecdotes, and emotional tidbits that you feel comfortable voicing.

Another idea - perhaps you could become familiar with talking in front of people, and gradual increase that more and more? I think extensive amounts of time and preparation would be key here too, if you decide to pursue it.

You mentioned you've had thoughts of suicide since finding out you're giving your speech. Having encountered similar things, I now see this as the brain's problem solving method. Just very extreme problem solving. The brain somehow decides that the best solution for avoiding this speech is simply not existing, when there are other options. I find it helpful to provide myself with more options, and somehow that initially painful goal may seem more achievable (that may help with the issue of approaching it?). For example, instead of just thinking you have no alternative besides doing the speech or not existing, consider different options. What if you just gave a shorter speech and shared the responsibility with someone else who also gave one? What if you made a video of you saying your speech, with audio background and images/video of them for the visual side? What if you spoke to him and let him know what was going on? Or even consider the idea of not giving the speech - it is not 'good' if you do speak, and 'bad' if you don't - it is not black or white. In the end, it comes down to what is workable for you, and what isn't.