Do i just let it all slide and act like it don't bother me or let the mom and exwife win and leave???

okay, my fiancee and i have been together for a year and a half, between both of us, we have 3 kids(mine, his, ours). he exwife came back on the picture and is now more part of their daughters life, they always text each other, he left his phone with me, he was trying to sell a car, said he may get texts about the car. his exwife text him saying remember that song i melt by rascal flatts. kinda makes me wonder if his exwife is trying to break us apart along with his mom cause ever since the exwife came back, his mom quit talking to us and became buddy buddy with the exwife and wants nothing to do with the child we have together. what am i supposed to do? i tried to talk to my fiancee about all this but he is such a nice guy and i am tired of him getting used all the time. his exwife uses him like crazy cause she don't have a license so she depends on him to take their daughter to her and it drives me crazy cause they fight once a month. it makes me feel like his mom and exwife are scheming to drive us apart. oh, did i mention his own mother don't have pictures of us or our child on myspace anymore, only the exwife and their daughter???