Stepdad vs biological dad.. I’m lost.

So my biological father seen me until the age of 3, my mother and him had some sort of issues in the past and we lost each other. I am now 26, in that time I was raised by my stepdad who I thought was my real dad until the age of 21. He was amazing, the best dad anyone could ask for and still continues to be.

I searched for my biological father for 5 years just out of curiosity but couldn’t find him until one day I did.

Now my biological dad and step dad know of each other and my mother told me deep down my step dad knows he isn’t my real dad, my mother had an affair and that’s how I came along.

Anyway, I’ve been building a good relationship with my biological father for the last month, it’s been amazing.

But it’s now getting to the point I don’t know what to do, I can’t tell my step dad because it would break his heart and I would never hurt him like that, but I can’t keep going away to see my biological dad in another city without step dad getting suspicious.

Some people are telling me to talk to my stepdad and tell him, but I just can’t, he’s so special to me and my biological father is too. I don’t want to choose between them and I don’t want to lose either of them, this situation is really causing me some serious depression now because I feel like an awful person for doing this. Somebody please help me, anyone who’s ever been in this situation. Do I keep lying to my stepdad and making excuses for when I go or do I tell him and risk losing him?