Crooked boy

I have this bad boy for a couple of year now and never realy took care of it. It spent its first year home potless on its side 😅 it was just wee lad but it just keep going and going. Its persistance gave me the will to take care of it now but I know nothing about cactus. Its seating in cheap dollar store dirt and get water once every couple of month. My biggest issue is that its leaning a lot! If I remove the trust it will just fall. What type of soil should I use, is my pot big enough and how do I take care of the leaning problem? I feel like it deserve a real chance 🌵