Having difficulty opening up to loved ones

24M. Been depressed for the last 10 years. I won't get into too much detail and bore you all. Lost my dad when I was 4, happened in front of my eyes and I grew up with a loving and caring mom. Have a gf of almost 8 years, dreaming of getting married soon. Whatever I am now, I owe it to them. They pushed me to be a better person. They pushed me to aim higher. But the problem is that as I pushed further I got tired. I feel drained more and more every day. I cannot talk to them about this because I do not want to be a burden to them. I don't want them to know that I'm not fine. I've been playing the role too well for years but recently I feel like I cannot keep it up anymore. I feel like I don't have any energy left. With each day passing I feel more and more exhausted. I don't have the motivation to do anything right now. I don't have anyone else in my life that I can ask for help from but my idiot brain just doesn't let me. I cannot control my thoughts and sometimes I spiral out of control. I get locked inside my own brain for hours, alone at home. I want to ask for help. I want to find a way. I know some will say "Just go talk to them" but I physically cannot do it. It makes me cry every time I think about talking to them. I don't know if this post was to blow off steam or a cry for help, my mind is messed up rn. I'll just add the venting flair so I don't misguide anyone. Thanks.