See my response to your other topic.
I would add - your mother loves you and wants you to be okay. Yes, telling her would be stressful. But it would also show her how close you feel to her.
A lot of addicts relapse. It's almost a given with addictions of any sort - drugs, cigarettes, alcohol, you name it.
Getting clean is a process. It's probably going to be a lifelong process.
One thing you might want to do is means blocking
. By that I mean: keep the paraphernalia out of your home. Don't hang around with anyone who uses (and yes, I mean your abusive boyfriend, too). Don't go to the places where dealers hang out. Physically separate yourself from everything to do with meth. It's not a perfect solution but you should not be immediately looking for perfect solutions. Instead, you should be looking for decent solutions which will help you get by as you get stronger.
You can do this.