Hey! My names Ethan. I'm a mechanical engineering major too. I'm a 5th year. Here's my shot at trying to cheer you up.
Failing classes is part of the major. I've retaken all of those classes you mentioned. Materials and thermo I hated the most. Circuits I was just lazy and depressed. But I'm working on that and I figured I could maybe help you out.
First thing to know is you need a routine. It took me a long time to figure this out but it works. Find a hobby. An outside hobby. I know, we're antisocial weirdos, but yes. Go outside. I frisbee golf or skateboard on week days and go paddle boarding on the weekends with friends. Work this into your routine and don't miss it. Make time for it. It's a great stress reliever and it keeps your energy levels up. Which you mentioned were pretty low right? I get it. Been there. I'm actually still there. Being engineering majors doesn't make us superman. We need support too. I have 5 really close friends. I've known these people for the last 5 years. Funny thing is only one of them is an engineer like me. The other 4 are graduating in 2 weeks and then it will be me and my one engineering friend next year all alone. We'll have to remeet people and make new friends and it hurts y'know? But this is where your routine and stress reliever comes in. It will make you feel better. Trust me. So when I'm feeling down I stop what I'm doing and go have me some stress relief time. I've been studying early and then skateboarding between HW sessions and then hanging with my friends so I can make the most of what little time I have left y'know. Trying not to be depressed in front of them is hard. Sometimes i just wanna cry because Im sad that they'll be gone. But you just gotta push through. Do anything to take your mind off that thought. Or maybe go cry in a corner and get it all out as quick as possible and then go back to doing your thing, because I'll tell you, it's really hard to study for a test when you're trying to hold back tears. Better to let them out now and get back to studying sooner. Either way, learning to manage this stuff is a good habit for engineers and just a good life skill in general.
Really sorry about all your personal problems you mentioned. If therapy is your thing there's always that too. It's not really been helpful for me but if you haven't tried it then I would give it a shot. It's nothing to be ashamed about. Plenty of people do it.
You just gotta keep pushing through. Stick to your routine, manage your stress and give yourself a little personal time y'know? Goof off between HW sessions like me. And realize that failing a class, or even a few, doesn't mean you yourself are a failure too. Sometimes some classes are harder for others. We all have our strengths and weaknesses. I suck at excel but I can build you a robot ez pz.
Anyway. I tried to bring up everything in your post. I hope I helped a little. Seriously. Message me if you wanna talk about anything. I get it. Engineering is rough and it's even worse when your family or social life is fucking you over too. My parents divorced while I was young so I have a good idea of what that's like. If you have any questions about anything or just wanna vent then I'm all ears and I hope you feel better.