Want my best friend to creampie my pregnant GF

I am 23m. A few months ago my best friend showed me videos of him and his ex GF, who was my first crush. He was standing over her naked and his penis was on her face and in her mouth. I pretended I didn’t want to see it, but I couldn’t stop thinking about it. He has the most perfect penis I’ve ever seen, easily 7+inches and amazing colour, length/thickness ratio, and just the right amount of hair. I’ve known I was bi, but never been attracted to a man I knew personally until then. I was more jealous of his ex gf (my first and longest lasting crush) than I was of him. Soon after I became honest about these things with him and not for a second did he make me feel bad. I even told him I fantasize about him fucking my gf if I got one, and he said he’d do it (we were drunk at the time). Today I have a gf I love more than anything, and she’s 12 weeks pregnant. She knows about my fantasies, and with some prying, admits I am the shortest penis she’s been with. She also says I am the best she’s been with, witch I believe without her saying as she clearly has powerful orgasms at my will. I am on the higher side of average size, but I get off when she talks about how it’s the smallest she’s seen. Back to my best friend, who is by far above average, and just all around a more masculine, traditional man than me, who I trust and value more than anyone. I go to sleep almost every night imagining him fucking my pregnant GF, and cumming inside of her for me to eat her out after. I doubt he would still want to cuck me, let alone let me go down after, but the fact he said he’d do it before, and knows I’m sexually attracted to him. Plus the fact my GF somewhat open to it, and pregnant so he could come inside, turns me on so much. It bothers me that this is my greatest fantasy right now, but I’ve told the two people I care the most about and they don’t seem to think it’s bad. Both even seem open to it. I wish I had the balls to try and make it happen, but I don’t know that my GF and BF would enjoy it in reality. And it’s too much to ask for them to do for me. I should probably just be happy I already got to see him with my first crush, and don’t want to do anything that would make him actually think I value him less. Thanks for reading if you made it this far, just wanted to share my situation with someone not involved.