I'm so scared right now that i think i might do something silly

my husband is a crack & heroin user has been 15 yrs first 8 yrs daily last 6/7 he relapses ever 1 - 2 weeks with a crack/heroin binge. he's made my life hell for this entire time but i've totally been THERE for him and how does he repay my support? By sexting loads of different women who he's met via his phone using various apps. I found some facebook msgs with 1 girl of 20 in new york (hes in his 40s!!) and he's telling her 'i ****ing love u' and 'ur so hot' when I confronted him he said it didnt MEAN anything as he was doing it for fun!!! He didnt offer me any form of apology and when I was crying he just blanked me!

When drugs were his distraction THAT was bad enough and I thought that was as bad as things could get, but these other females I just cannot deal with!!!!!!! I felt really disrespected with the drugs thing but now this betrayal by him it's like my feelings and our (already fragile) marriage have been trampled in the dirt!!! He's told me (in the not too distant past) that he didnt know where he'd have ended up if I hadn't stuck by him with the drugs thing (as nobody else did - just ME the mug!) and yet this is how he repays my sticking by him??!! I seriously think the drugs have messed up his brain as it's like he's had a complete personality transplant!!!

I wish I could pack my stuff and leave and if I could I WOULD but I can't as I have severe anxiety problems and agoraphobia and it's like he uses that to his full advantage knowing that I can't just up and go!

Please can anyone just listen even if you can't offer advice? I feel so alone right now.