Is quitting the right decision? Working 7 days a week

I graduated in the summer and have been working full-time since September. Alongside this, I kept my part time job in retail on the weekends. I've had this job since sixth form and thought it would be fine as I like most of my colleagues and it gets me out the house. I don't have many friends or atleast the type of friends that are free to hang out each weekend so I always thought what would I at home. It's now January and I've had a no of health issues and I'm feeling extremely burnt out for the first time. My family keep telling me to quit and today I put in my resignation. Idk why but I feel guilty like I shouldn't have quit. I am hoping to just focus on my full time job and find another one when the time is right I'm currently on a fixed term contract in the full time role so I thought the part time retail job would offer a bit of stability but I don't think I can keep working both for much longer. I never get a day to rest. The money is not worth it either. My tax code has been messed up for months on my full time job and now that I tried to fix it, I'm getting a measly amount on my retail job because it's all taxed. I started a sharesave scheme with the retail job which I haven't completed so I'll have to get the money back for that. I'll also miss the discount a lot lol