AITAH (27M)For seeing my old friends ex (29F)?

So this guy I served with in the military for years , his ex gf from a couple years ago expressed her hidden attraction for me . We started going on dates , but nothing sexual , a few kisses and cuddle sessions but nothing more . I haven’t taken it to the next level because I feel guilty . I remember him talking about how he loved her , and even voiced that he thought she was attracted to me . She mentioned that he begged her not to do anything with me after they parted ways . Me and him haven’t spoken for awhile but it still doesn’t help . Shes looking for a relationship and she wants to sleep with me , but for her sake I don’t want to because I don’t know if I can get past this guilt . I don’t want to make her wait for my own obstacles nor do I want to betray everything me and this guy had been through together on deployment . Am I the asshole and should I let this go ?