Should I divorce or just leave?

I'm so distraught...after many years 13 years.. many ups and downs.. divorce getting back together other women twice to my knowledge.. serious issues that my heart is tooooo tired to mention... i see my husband is communicating with another women.. he recently said in facebook contact that he loves her.. he cant resist her. ..yet he told her most recently not to call anymore because 'she knows where it will lead'... i know he hasnt had .. theyr in 2 diff parts of the world.. but what bothers me more is that he said he loves her.. theres 5 kids involved.. we've been thru so much.. where in 2005 that was the last separation... we got back together.. i agreed to forget abut the past. although i cant most times. i think of him with other women although he married them.. but im muslim so thats allowed.. i just didnt know at the time and was workin hard for my family not knowing hes screwin around.. long story.. twice that happened. anyway my ? now is even though he said he was young immature and hated what he did but is happy he realizes what i mean to him and that he loves me and were still together.. i still feel very slighted.. angry.. i want him to feel my pain... we' were generally happy with eachother..best friends... partners etc.. until he decided to sow his holy oats.. cuz he was raised muslilm unlike me, with no girlfriends etc... thers also other issues.. bipolar disorder i presume no diagnosis but he gets xtremely dperessed periodically just as all the sites say.. he fits the picture perfectly.... dont know if i should still b supportive or just give up...im tired pregnant now again. what are your thoughts.plz help asap