I love my boyfriend but i dont know if I should put all my trust in him... does he love me the same???

Me and my boyfriend are in love and we have been togther for a year and like 2 months. We have been living together for a while and at one point he got me an engagment ring.. and we were very happy but we fought alot. Then one day out fight led him to take the ring back and we didnt see eachother for 3 weeks then i read him e-mail and he had been talking to girls and telling them he wanted to see them to get away from me. Telling them how he made a mistake buying me a ring, well i confronted him and we broke up. And even tho we were apart we still called eachother everynight and said we loved eachother. I began to lose hopw and i started talking to other guys and kissed a couple. But fell back into the arms of my true love. Well we got back together and one day the subject of me kissing those guys came up and he almost broke up with me again.. but we got past it. But occationally he has those moments where he threatens to break up with me agian and i worries me. We do live together again and we are for sure in love. So now and then the subject of the ring comes back up and he says i should be getting it soon. Another thing is we live with his mom and we want to get an appartment... so my question is should i put all my time and money in an appartment and except the ring or just take things a bit slower. I Do love him more than anyhing in the whole world but im so scared he is going to take the ring back again and i cant deal with that heartache again. And if we move out... what if we break up?? id be clueless. PLEASE HELP.