SO ex troubles

I usually don't post but I'm really overwhelmed with emotions. I've been with my boyfriend for almost a year but we are extremely serious with each other and have been talking a lot about getting married lately. The problem comes with his ex girlfriends always trying to come back into his life. Two of them have recently contacted him begging him to get back together with him and he told them no. He always tells me when they contact him because we try not to keep secrets from him. One of the girls has texted and asked for sex multiple times and even asked to pay for sex once. This girls was his first love before me. That's alright, I'm not jealous of his past relationships, but sometimes it makes me feel inadequate when they come back and try to remind him of what they had together. Last night his first ex girlfriend texted him saying her mother passed away and wanted him to comfort her. I genuinely feel bad for her, because it's a terrible thing, but why come to him? She has a boyfriend, and my boyfriend has been telling her to go away for the longest. But we both know that he shouldn't be mean in this situation. It don't know what to do, and if this will keep up as long as we're together...