How do I keep my mother distant?

Do you mean you are starting college? And you think she doesn't want you to go, or she doesn't want you to succeed?
If you want to go to college, and you think she will do something to stop you, you just have to prevent that.
The simplest way is just not to depend upon her. Make sure that you can go whether she keeps any of her promises or not.
For instance, if she says she will pay your tuition, fine, but be prepared to get the money somewhere else if you have to. After all, you are an adult and she is not obligated to take care of you. It is good of her if she does.
And by the way, I have to say you have no idea how she feels about your father's suicide. The suicide of somebody close to you is so profound that it is near impossible to express. Especially since she had to go on caring you, a toddler, afterward. She could not possibly express her feelings to a young child. And your reaction to his suicide will be very different from hers, because you were so young when it happens. So I advise you not to judge her on that issue.
Your college will probably have counseling resources to help you out too.
Another possibility which some people choose, is to get a job and save up your own money so that you can be independent. Personally, I recommend this anyway. To experience self-determination in the "real" world can give you a better preparation for college.
I'm just talking in general principles of course; you have to decide your own path.