AITA for dating someone new

I’ve been torn up about this and maybe need some other opinions outside of my family.

I dated someone for 4 years who ended up being my best friend. We moved in together and even moved states together. We love each other deeply but I’m romantically not interested anymore.

Year 2, 3 and 4 I Initiated a break up because I knew my heart wasn’t in it. However we stayed together each time because breakups are emotionally hard and neither of us were ready for that.

Over the years I initiated breakups because I feel I’ve grown out of romantic feelings, mostly because my family doesn’t approve and because I realized I still had feelings for my first love.

First love and I were suddenly separated one day years before the best friend entered the picture. We were apart and forced to ignore feelings, so the first love never left my heart or mind. We just disappeared from each others lives. One day in bed together, the next night alone. It would be another 10 years before reconnecting because we both moved around for work.

After some eat pray love soul searching I realized I wanted to respectfully end my relationship with my best friend and seek closure with my ex, whatever that looked like. I have had a hard time moving on in life romantically because I was still holding on to the first love.

So despite the consequences I broke up with my best friend. We went to therapy together and had about 6 months of adjusting and endless deep closure conversations together before I officially moved on. But I had been moving toward separation and using my new love interest a strong hold reminder not to be confusing and go back to my best friend just to comfort them (as I had done before in years 2, 3, and 4).

It could’ve been a short disaster or a long long story. I had no clue but knew it wasn’t fair to keep the best friend waiting while I figured things out.

I was honest with them and even though the conversation was hard, ultimately it was the right thing to do.

We have worked hard to stay good friends and roommates, respecting these new boundaries.

After almost a decade my ex and I were finally able to reconnect.

Flash forward to now, we’ve een back together for almost a year. So it has been about 1.5 years since the breakup from best friend, and 1 year with the new partner. The timing was divine intervention. Honestly perfect.

Except, I still live with my ex partner / best friend. They are my dearest friend. I can’t bear to tell them I’m interested in dating someone new.

When we ended our relationship we considered our commutes, the costs to move, our recovering credit scores, and deposits for moving, etc so we agreed to still live together.

And I’m not just dating this other person, we’re engaged now. This is my first love, we always discussed marriage but time and work split us apart. But now we are both available and we have a chance to rekindle we don’t want to miss it. But I don’t want to upset my ex partner by telling them I’m dating someone else and wanting to move on soon.

I don’t want to lose my best friend. But I feel I have to because they’re also an ex. They have been there for me while this other person wasn’t able, and to abandon the friendship would be heartbreaking

So neither my best friend or my partner are asking me to do this, but I feel I have to pick one for my own sanity. Keep my bestie and let my fiancé go because I would never ask them to accept me living with an ex. Or let my fiancé go because friends are the true prize and we are the same damn person by now.

When discussing marriage with the best friend I never wanted it because I knew in my heart I’d already betrothed myself to someone from my past. So it was never something we agreed on. Kids or marriage. The best friend agreed to forego those things for me, which made me even more resolute in my decision to set them free from me. I knew I couldn’t ask for that kind of sacrifice

So we’re still present in each others lives. My family is part of their support system now, they are an honorary family member but not as a spouse for me (long ordeal with my family). I love my family and I envision a happy union with my spouse and family and this partner didn’t align with that. Bc I love my family and they have been good to me, I’m willing to find another partner they approve of. I want us all to be happy.

I don’t want to ruin the living situation with the best friend because we have 1 year left living together. They’re such a good friend and I don’t want to hurt them. I want them to be a part of my life and even be by my side at my wedding but that’s cruel because I know they may still have feelings for me or feel hurt I rejected them but not my fiance

We’ve been broken up for quite awhile and I am in a new thing but don’t know how to break the news and if it’s worth it. We agreed not to discuss these things after breaking up, but if I’m planning to start a life with someone new doesn’t the current roommate deserve to know that I am soon to move on?