Should I break up or is it just a mood?

Lately someone I used to know came back into my life I knew him while I was w my current bf and I caught feelings for him when he was helping me through my problems with my bf...and it’s bringing back old memories from when I was unhappy w my my bf...I always wondered what it would be like to be with him but I was always in a relationship...but Me and my bf have been great recently but deep down I’ve been having doubts. Everyone tells me I should break up but I’m afraid of being alone...and I do love him. I just feel really conflicted rn...what’s your opinion?