Not knowing how sick your mom is, I don't think you should burden her on top of what she is already dealing with. If she is seriously ill, or heading towards it, the last thing a parent wants to know, other than their child having a fatal physical disease or something along those lines, is that their child is unhappy and is contemplating suicide. She may put on a brave face for you, and even be there for you, giving you the guidance you need, because that's what a parent does, even when they're not at their best, but it will still weigh heavily on her emotionally, and that may not be the best thing for her.
I don't think it should be considered a burden to open up to your own mom.
Parents are the ones who bring their children into being, after all.
Being there for their kids comes with the territory, in sickness or in health.
I think regretting the missed opportunity to open up to her will hurt more than regretting the opposite.
I can't imagine she is totally oblivious to
@Circles pain anyhow.
I personally know what it's like to have nobody else and sometimes you just have to go to the only person you can.
It's not fair for OP to become ill via their own internalizing either.
It could result in something even more painful to their parent.
It's up to OP, but I think being open and honest is always the best course of action in this type of situation so long as you aren't fearing for your safety.
And decent mothers (or guardians) are usually always the safest people to go to.
If it were my kid, I would want to know what was going on with them, even if I was on my deathbed.
But perhaps that consideration and concern is an anomaly.
There are ways to be considerate of the other person's predicament while explaining your own.
It can be a two-way street of support.
It's a gray area. But with parents, I don't think any child's suffering should be taken as a burden to them.
It might be different if the parent were incoherent or something, because then there wouldn't be much point in telling them things, but I'm assuming that's not what's going on here.
Again though, not my decision, I have no idea of the other details that could influence what the right course of action may or may not be.
I also have my own history with my own parents which could lead to certain biases that color my advice.
But that probably goes for everyone.