I'm sorry to hear you are in this difficult position and share my compassion, along with sincere wishes for your well-being and that of your children. There are other parents on the forum faced with the same difficult decision, my heart goes out to all of you.
In response to your post, here's some reading material that may help you with sorting out your perspective and goals:
(relates to feeling like a burden)
https://sanctioned-suicide.net/threads/a-stoic-perspective-on-impulse-and-courage-in-ctb.32674/post-603462 (the whole thread is good, but I linked to the most relevant comment)
https://sanctioned-suicide.net/threads/a-shift-in-perspective-that-may-help-to-accomplish-ctb-or-anything-else-one-seeks-to-attain.40371/ (see also comments by another parent,
@AcornUnderground, who has health issues that have led her to the choice of assisted suicide. I see posted on your thread here while I writing this post.)
https://sanctioned-suicide.net/thre...urvival-instinct-whats-your-take-on-it.40204/
Not trying to pump up my own threads here! They're just things I've considered that you also consider, and it's easier to link what I've already said than to state it all in a comment here (and it also shows what others have said as well, whether in agreement or disagreement, so it's not just my perspective). You and I have different reasons for considering and pursuing ctb, but they relate when considered from the philosophical stance in the second link. We both have goals of being able to accomplish what we seek once we determine that is indeed the choice we've made.
If I remember any other resources, I'll be sure to share them. You may find some in the pinned Resources Compilation thread, which is about more than just methods, including links to considerations of perspectives that support one's right to a self-determined exit.